Updated 03/12/19

The BMW N54 Twin Turbo Inline 6 Engine is a glorious powerplant, but you need to make a couple of choice BMW N54 Mods to turn your 335i from a sedate cruiser into something a little more beastly. As tuner cars go, the BMW N54 Twin Turbo Inline six responds incredibly well for modification gains for the N54 are often double what the same mod would yield on another car – with modded 335i’s often hot on the heels of the V8 E9X M3 one has to wonder if the N54 is the reason why the F80 M3 / F82 M4 boast a Turbo Six underhood. So with that in mind, we’ve put together this updated list of Bolt On Mods for the BMW N54 that will get you to the next level. 

The following are 5 modifications that will take your 2007-10 BMW 335i (E9X) from stock to FBO – aka Full Bolt On status. Making these key tweaks to your E9X will really wake up the car and can boost your output by more than 100 horsepower. By following this stepped upgrade path, your BMW 335i will be ready for the next stage and deliver optimal performance.

Before we get started here, there’s one thing you need to take care of before you start modifying the car. Cobb Tuning and Burger Motorsports will both turn your car away for tuning unless you’ve done this very necessary maintenance service. What are we talking about?

This is the OEM intercooler off of a 2007 BMW 335i – we actually had to put a cup under the OEM intercooler to collect all the oil to keep it from making a mess of the shop. See how the entire intercooler has a nasty yellowish green sheen to it? That’s OIL. And that’s why your intake gets as disgusting as it is.

God, that’s nasty. And to think, the inside of your intercooler likely looks JUST LIKE THIS!

Modern engines like the N54 and N55 family of engines feature Direct Injection fuel systems-  traditionally, in a multi-point fuel injection system, you’ve got your fuel injector mounted in the intake runners, which sprays down the inside of the intake valves and intake manifold runners with gasoline, continually bathing them in gas (an excellent cleaner) and which keeps them clean and flowing smoothly. It’s not just BMW using direct injection– most modern engines feature some version of direct injection, and notably Ford EcoBoost engines also employ the technology.

Walnut blasting to clean all the carbon off the intake valves so your engine can perform as it was intended and can respond fully to your mods – and BMW recommends Walnut Blasting your N54 every 30,000 mi.

What is Walnut Blasting? Why should I do it? For one, don’t actually put walnuts in your intake, but we’re talking about Walnut Shell Blasting your BMW N54 or N55 BMW E90 335i, E92 335i, F30 335i or F32 435i – though what we’re about to say applies just as much to the S55 of the all new F80 BMW M3 and F82 BMW M4 and the entire N20 4-cylinder turbo family. While it sounds silly to walnut blast the car, both BMW and your dealer actually recommend you do this every 30,000 miles! Basically, oil vapor ends up coating the intake valves and like cholesterol clogging your arteries, the accumulated gunk is impeding the airflow at your intake valves. For further explanation of why the service is necessary, check out our writeup here.

Here’s what Senior Mod Expert Alan Wei had to say about how the car felt before and after doing the service on his E92 335i:

“The car feels way more responsive, it doesn’t hesitate as long before responding to the throttle, and boost hits harder and the car runs more smoothly. It’s like the motor’s new again. If your N54 has more than 30k on it, the difference in performance alone makes walnut blasting your BMW N54 or N55 a MUST to get the most out of your performance mods, and your tune.”

And here’s an actual photo of Alan’s motor right after doing the service. You can actually see the valve now!

ModBargains now offers Walnut Media blasting service at our install shop, Mod Auto – for a limited time, we’re offering this service for just $495 – it’d cost you $410 in materials/tools alone to do it yourself. Save yourself an afternoon of frustration and let our professional Technicians clean out your intake valves to make your N54 as snappy as the day it left the factory again. Take advantage of this pricing while it’s available – call us today at 714-582-3330 to schedule your Walnut Blasting BMW Engine Cleaning Service today, and we invite you to talk to Senior Mod Expert Alan Wei to hear about the difference it made in his car first hand at x8006.

With that out of the way, your engine is clean and ready to respond to your modifications- so let’s get started modding!

1. A Tune

Tuning the ECM is the #1 way to make more power right now with your N54-powered Bimmer and truly unlocks the full potential of your twin turbo inline 6. Most tuners are plug and play with minimal actual effort required to install them – in fact, it’s often as simple as pressing a button. By changing parameters such as boost pressure, timing, fuel mapping, throttle map and other key functions, a tune will dramatically alter the character of your N54 engine. Output increases are significant and only go UP from there as your level of modification increases – you can pick up up to 51% horsepower gain with a Stage 2 aggressive tune (requires full bolt on) – and with a Cobb Tuning AccessPORT for BMW N54, reflashing is quick and requires no changing of physical parts for an immediate +60whp / +80wtq gain over stock – before you even get around to doing any other mods!

Tunes allow you to adjust your engine’s programming as you add bolt-on parts, offering you flexibility to have your tune adjust with a different map as you upgrade. Several different tunes are available, so it’s up to you to determine which one is best for you. If you’re unsure, you can always consult a Modification Expert.

The Consensus among enthusiasts is the AccessPORT is the way of the future for BMW N54 mods. Below are some reviews from real enthusiasts like you.

“I have a stock 2008 e90 335i. I previously had a JB+ installed and I thought I was happy with it, until I came across the COBB Accessport and I was immediately drawn in to the idea of not having to mess around with the electronics of the car and having to uninstall hardware every time I went to the dealer. Another bonus for me was the fact that the unit comes with free future upgrades of maps, because I did not want to buy a piece of hardware and it becoming obsolete a few months down the road through the release of a newer, better one. So I took the bath and bought it. Thanks again to Alan at ModBargains.com for the great assistance and hooking me up with a great deal on this unit.

So I loaded the map for 93 octane and went for a spin… all I can say is holy crap! This car is a beast now! I cannot believe that this kind of power has been “reserved” in this car and the COBB was able to unleash it. Power delivery is smooth, and I had no trouble driving in wife-in-car mode, but push that accelerator down just a tad more and watch out! I have trouble keeping the rubber on the road now so I guess I will be looking for some new tires pretty soon, as the stock run-flats are clearly not up to the task any more.

Great job COBB and Alan at Modbargains.com. Happy customer here!

Oh, and anyone coming from a JB+ or stock car and not being totally blown away by this tune needs to get their butt-dyno examined.”
– kaigoss69@E90post.com

That’s a pretty glowing endorsement. And it goes on (click here to see more firsthand reviews).

Listed below are a few tuners available for your N54 – OBD II reflash is the preferred method of tuning, as nothing is physically modified in the car’s wiring harness, and since the software is rewritten, it’s not something trying to fool the stock computer into doing something else. All in all, these are simpler and much more painless to use.

Cobb AccessPORT V3 ECU Flash Tuner BMW N54 (AP3-BMW-001)
Stage 2+ 51% HP 55% TQ Gain – Installs through OBD II

These options require physically modifying the car’s electrical system, which takes 45+ minutes each time you install and uninstall, and most of these are not available to people living in California. While simple, these are inexpensive and “get the job done.”

BMS JB 4 Processor for N54 Engine (NOT AVAILABLE IN CALIFORNIA)
Up to 80hp gain over stock, up to 250hp gain with supporting modifications – Plug-N-Play Piggy-Back Type

BMS JB Plus Processor for N54 Engine
(NOT AVAILABLE IN CALIFORNIA)
Only +40hp & +50tq – Single-Point Plug & Play – Simple, no-frills power gains with the lowest cost of entry.

Whatever route you decide to go, a tune is going to be the most bang for your buck of any of the modifications you’ll do to your BMW N54 turbo six.

2. An Exhaust System

Most people upgrading their exhaust do so for the sound, but on the N54, there’s some real power to be had in upgrading the exhaust system beyond just an improvement in engine tone. There are several performance exhaust options, ranging from quiet to aggressive. Since exhaust can be subjective, the right exhaust for you may not be the right exhaust for your friend who likes his car louder than you do – and so on.

For these reasons, it’s important to do your research and look at all the options available to you before making your decision. These systems offer a gain of around 10hp at the lower end of the spectrum, and that number will increase as you add other modifications. While not the biggest gain by itself, like the intercooler, a good high flow exhaust is an excellent supporting modification that will have your vehicle ready to go to the next level. Here are just a few exhaust options for the E9X 335i. We have videos available so you can gauge sound levels for yourself, and you can always ask a Modification Expert for guidance for what sort of system is best for your needs.

COBB Cat-back Exhaust for 2007-13 BMW 335i/is [E90/E92/E93] w/Dual 4in Tips

*Remus Axle-Back Exhaust for 2007-13 BMW 335i/xi [E90/E92/E93]

*HKS 335i Exhaust (E90/E92/E93)
(+13 HP, +8lb/ft Torque)

BMW Performance Cat-Back Exhaust for 2007-13 BMW 325i/328i/330i/335i [E90/E92/E93]
(+5WHP / +3lb/ft Torque)

These were just a few exhaust options for the N54-powered E9X 335i, you can always ask a Modification Expert for guidance for what sort of system is best for your needs.

Interested in spicing up the look and performance of your N54? Ask the Mod Experts what exterior upgrades are available for your car to change the style of your ride. Call us at 714-582-3330 for expert car mod advice and schedule your installation at the Mod Auto shop today.

3. An Intake Upgrade

Dinan Carbon Fiber Intake for N54 BMW 135i/335i

An Intake is not necessarily the biggest gain in power for a naturally aspirated car, but that’s not the case here! Turbocharged cars have a lot to gain from the use of an aftermarket intake designed with performance in mind.  The biggest benefits of an intake are improved throttle response and you “hear” your engine more under wide open throttle – turbo and supercharged cars will hear more  turbo spool and a few horsepower at the rear wheels. Occasionally, your mileage may even improve with a performance air intake.

There are options ranging from “OEM++” for a like-factory look that’s low key and stealthy for those that don’t want to “look” modded, or a well engineered dual filter cold air intake can deliver up to 27HP and 34lb/ft of torque. With over THIRTY options, there’s too many to list here- cruise on over to the E90 Intake or E92 Intake pages to browse our full range of intakes for the E90 and E92 335i. Listed below are just a few examples of the different types of intake upgrades available.

*Injen Cold Air Intake for 2006-12 BMW 135i/335i/335is [E82/E88/E90/E92/E93] N54

An Injen Tecnology Dual Cone Air Intake for BMW 335i. As we’ve discussed before, the OEM intake for the BMW N54 engine is very restrictive, and even before tune the Injen Intake yields 13whp / 13wtq for noticeable but modest gain.

Beyond just the horsepower gains, throttle response is sharper and you also get the added benefit of better hearing your turbos spool. The Injen Intake is also CARB approved.

*Injen Cold Air Intake for 2006-10 BMW 535i [E60]

(+9WHP /+14WTQ)

VRSF Dual Cone Air Intake for 2007-12 BMW 335i/is [E82/E90/E92/E93] N54
(+10-20WHP; No Heat Shield, Cone Filter Conversion Only)

BMS Dual Cone Intake for 2007-10 BMW 135i/335i/535i [E82/E90/E92/E93/E60] (Not Currently available in California)
(+10-20WHP; No Heat Shield, Cone Filter Conversion Only)

To get the most out of your intake, you can bolster them with a set of Air Intake Scoops, like the Dynamic Air Scoops for BMW E9X 335i from aFe seen below.

These ensure your intakes are being fed more cool incoming air than the stock air duct allows.

Don’t forget the Chargepipes!

The chargepipe is the part of the intake system after the turbo and intercooler, before the throttle body. It’s the part of the system that’s filled with boost pressure and so, it makes sense that it would be under a lot of stress. Unfortunately, the OEM part is a rather brittle piece of plastic fitted with slow, leak prone diverter valves.

BMW, in their infinite wisdom and brilliant choices for materials, decided to make the chargepipe out of plastic. And that’s fine – for a while.

Most BMW N54 and N55 engines are more than 5 years old now – and what this means is that 5 or more years of aging, oxidation and cycles of heat as the car warms up and cools off each day as you drive has taken its toll. The plastic gets brittle, and when you put pressure into a brittle plastic thing, it explodes – just like those soda bottles full of dry ice from when you were a kid. If you’ve ever seen a dry-rotted tire, you know rubber degrades just from being exposed to the air and environment. Plastic also degrades with time, just at a different rate.

So you’re going to have to replace the chargepipe no matter what you do – and it’s worth saying that the plastic material is not ideal for sealing things up anyway, meaning that it leaks some boost, even when everything’s put together perfectly. This means replacing it will improve throttle response and performance – not to mention a performance chargepipe is probably less than what your local dealer will sell you the OEM chargepipe for, meaning it’s an economical preventive maintenance item.

If your chargepipe hasn’t failed yet, we hate to fearmonger, but it really is going to fail soon in all likelihood, and while it may not blow up like it’s made of C4, it will pop, and it won’t seal anymore. In the past year along we’ve been flooded with calls from people all over the country, in a panic to find a chargepipe to replace the one that exploded ASAP. It’s an epidemic; as if suddenly the plastic hit its expiration date.

What’s happening? When tuned, the plastic stock chargepipe and plastic stock diverter valve cannot stand up to the added boost pressure, crack and fail, causing boost leaks and other poor running conditions, not to mention robbing you of bottom end power on the order of 29wtq LOSS at lower revs.

Though the intake in this itself is stock, you can see an Evoluton Racewerks BMW N54 Chargepipe for Diverter Valves (rather than a BOV) eliminates the failure-prone OEM chargepipes which have been failing with greater frequency this past year as the plastic becomes brittle with age.

Complimenting the chargepipe is a set of Turbosmart Kompact Plumb Back Diverter Valves for BMW N54, eliminating the 26ft/lbs of torque normally lost to boost leaking out of the leak-prone OEM diverter valves.

About that 29wtq LOSS in 1st and 2nd gear – why is that? The OEM diverter valves are plastic-  plastic is cheap, it sticks, leaks boost and actuates slowly. This slow actuation is about a second’s worth of boost when you’re in gear, creating a much laggier feeling car than it ought to be- the car will feel much faster with a Dual Port Blow-Off Valve or Plumb-Back Diverter Valve setup.

So, how can you prevent the chargepipe from cracking under pressure? Simple, replace that janky, cheapo piece of plastic with a hard N54 chargepipe from Evolution Racewerks paired with your choice of Blow-off Valve, or Cobb Tuning’s new N54 Chargepipe paired with a Turbosmart Plumb-Back Diverter Valve or Turbosmart Dual Port Blow-Off Valve to suit your style and taste.

The graph above is a dyno chart of a BMW 1M, completely STOCK, ONLY the diverter valves were replaced with Turbosmart Dual Port Blow-Off Valves – you can see just by following the dyno chart where the stock diverter valves are leaking boost, sucking up your power like some sort of awful plastic horsepower vampire. The torque gains throughout the rev range are consistent and picks up more than 25wtq down low where it counts, and you’ll really feel that difference in 1st and 2nd gears.

The above graph charts manifold pressure on the same BMW 1M as the last chart, again, with ONLY the diverter valves changed – with leak-free diverter valves, peak boost is sustained and held for maximum power. Turbosmart‘s N54 diverter valve setup works for most intakes and the OEM chargepipe as well as some aftermarket chargepipes, like Cobb’s N54 Charge pipe, but Evolution Racewerks N54 Charge Pipe features an integrated BOV and optional meth bungs and the Titek N54 Chargepipe features an integrated HKS SSQV blow-off valve, so you have a number of options available to you.

Evolution Racewerks has stepped in with a solution with the Evolution Racewerks BMW N54 Chargepipe – available in black or polished, which replaces the OEM chargepipe with a high flow replacement and even features a port for methanol injection (this comes plugged, in case you don’t run WMI).

The earlier N54 cars are especially vulnerable to chargepipe failure – Evolution Racewerks Chargepipes for BMW N54 engines feature optional blow off valves, like the HKS SSQV pictured above.

If you just want a straightforward replacement, a VRSF BMW N54/N55 Chargepipe is a great “budget” option but doesn’t have the same features as the Evolution Racewerks option.

One other direct replacement option we’d like to mention is the Cobb BMW N54 Chargepipe, which is patterned to directly replace the OEM chargepipe and use the OEM diverter valves or an aftermarket Plumb-Back BOV setup.

In addition to the low boost-pressure capacity, OEM charge pipe has a silencer baffle built in which also splits airflow and causes turbulence in the intake. By removing the turbulence caused by the baffles, you’ll experience increased throttle response, decreased turbo lag and an overall higher output potential. Charge Pipe/Diverter valve combinations are available with optional blow-off valves (for those who enjoy that cool “pssshh!” sound when shifting) and even optional Methanol Injection bungs (should you add Meth later for even more power). A charge pipe will also help prevent potential boost leaks. Making this upgrade now will allow you to safely run higher levels of boost later on.

*Turbosmart Kompact Dual Port Blow Off Valve BMW N54 (135i/335i/535i/Z4)

*Turbosmart Kompact Plumb Back Diverter Valve BMW N54 (135i/335i/535i/Z4)

Evolution RaceWerks N54 Charge Pipe w/BOV or Diverter for 2007-13 BMW 135i/335i [E82/E90/E92]

Active Autowerke Chargepipe w/ Blow Off Valve for 2007-12 N54 BMW 335i / 535i [E90/E92/E60]

COBB N54 Charge Pipe for 2007-13 N54 BMW 135i/335i [E82/E90/E92]

Forge Motorsport Diverter Valves for 2007-12 N54 BMW 135i/1M/335i/335is [E82/E90/E92/E93]

VRSF Charge Pipe N54/N55 for 2007-13 BMW 135i/1M/335i/is/535i [E82/E88/E90/E92/E93/E60/F10]
So whether it’s for the longevity of your motor as a maintenance item or for the 29wtq you get back, upgrading the plastic factory chargepipe under the hood of your N54 powered BMW is a great idea. Fit your N54 with an upgraded chargepipe today from the Mod Experts.

4) Front Mount Intercooler aka FMIC

VRSF Intercooler FMIC Upgrade for 2007-11 BMW 135i/335i [E82/E90/E92]

VRSF Intercooler FMIC Upgrade for 2007-11 BMW 135i/335i [E82/E90/E92]

As we mentioned in an earlier post, the N54 engine runs hot from the factory and benefits from reductions in temperature – an Oil Cooler is a necessity – and an Intercooler will further help reduce engine temperatures. An intercooler is ideally that “next step” that helps support your other modifications. 

The OEM Intercooler for the N54 engine is a little small – it measures just 510mm x 130mm x 110mm for just 7,293 cm3 of volume. This means intake air temperatures are much higher than they need to be – and with hotter intake temperatures, the air is less oxygen-dense, meaning it doesn’t generate as much power and can lead to detonation. An aftermarket intercooler can offer as much as a 90% increase in airflow, reducing turbo lag, increasing throttle response and spool-up. 

The Intercooler’s piping can be as much of a restriction as the intercooler’s lack of volume, so seriously consider an intercooler upgrade that includes larger inlet/outlet piping for the greatest benefit from your intercooler. What’s more, nearly all aftermarket intercoolers eliminate the nasty and failure-prone plastic end tanks popular as OEM units.

Long story short, having a front mounted intercooler means that your car can consistently produce its peak power, pull after pull – and also reduces turbo lag and increases throttle response and faster boost spool-ups – ballpark power gain estimates for Intercoolers alone range from 15-25 HP gain (at the wheels). Listed below are several popular choices for BMW N54 Intercoolers, but these are just a few suggestions. Take a look at the options available and decide which is best for your build, or you can always ask a Modification Expert.

*Evolution Racewerks Competition Front Mount Intercooler 135i, 335i/xi

*Mishimoto Aluminum Intercooler for 2007-2010 BMW 335i/335xi/135i [E82/E90/E92]

Cobb Intercooler for 2007-13 BMW 135i/335i [E82/E90/E92]

Wagner Tuning Evo I Competition Intercooler for 2007-13 N54/N55 BMW 135i/335i/Z4/1M [E82/E90/E92]
Wagner Tuning Evo II Competition Intercooler for 2007-12 N54/N55 BMW 135i/1M/335i/Z4 [E82/E90/E92]

5) Catted High Flow Downpipes

Cobb N54 Catted Downpipes

Besides a tune, a pair of Downpipes is probably going to feel like the single biggest “kick in the pants” upgrade. The Downpipes are the piece of exhaust that connects from the turbocharger’s outlet to the rest of the exhaust system.

Example Photo featuring race-only downpipes as mounted on your N54’s Turbos

The OEM catalysts are quite restrictive and limit how quickly your turbochargers can spool up. By replacing your downpipe with a unit or a unit with a high-flow catalyst, you’ll immediately notice better throttle response, louder and faster turbo spool-up and more overall power.

If you want your engine to feel more responsive, a pair of downpipes will definitely deliver the improvement you’re after. Listed below are several popular options for downpipes – for street use in the USA, we exclusively recommend opting for downpipes with a high flow catalytic converter. You can always consult a Modification Expert if you’re unsure what the best option for you might be.

COBB Catted Downpipes for 2007-13 N54 BMW 135i/335i [E82/E90/E92]
(+15WHP Appx, +15Lb/Ft Torque, up to +100HP/+120TQ when used with COBB OTS Map) 

Also Consider:

The five modifications above will take your car from stock to FBO status, but it would be a disservice to you to not mention a few other things to consider as well. These items are great “preemptive” mods, that resolve potential issues that may arise as you modify your N54 powerplant and help increase the longevity of your engine.

-Oil Catch Can

If you’ve ever taken your intercooler piping off and been amazed by the amount of nasty oil coating the inside of your intercooler, it’s time to consider an oil catch can. The main reason to add an Oil Catch Can to their N54 engine is to reduce/eliminate oil blow-by. Blow-by is caused when combustion in the engine forces fuel, air, and moisture past the piston rings and into the crankcase.

From there, the blow-by is released by the crank case vents back into the intake pipe. This occurs on all engines, but is notably worse on turbo engines due to the higher pressure in the combustion chamber. If nothing is done, this excess “gunk” will build up in the valvetrain, turbo, intercooler, and intercooler piping, robbing your engine of performance over time. If you have a lower-mileage car, this is a great boon to your motor’s longevity.

Mishimoto Direct Fit Oil Catch Can for BMW N54

BMS Oil Catch Can BMW N54/N55 Engine
*Mishimoto Baffled Oil Catch Can
*Mishimoto Compact Baffled Oil Catch Can

-An Oil Cooler:

It’s common knowledge that BMW N54 Turbocharged I-6 engines run very hot. Basically, any kind of spirited driving will QUICKLY have your engine operating much hotter than it should be, causing your oil to stop lubricating your engine’s moving parts properly and even overheat. 

This overheated condition can send your car into “Limp Mode”, making your drive home a whole lot less fun. Considering that BMWs are intended to be driven hard, this can make it hard to enjoy the ultimate driving machine. Considering that turbochargers are exhaust driven, they’re naturally going to be hot and accumulate a lot of heat. This heat generation, coupled with the fact that BMW E9X 335i models have a small radiator, means that under spirited driving conditions (like your favorite canyon), your coolant temperature can exceed 250 degrees – more than 20 degrees above what’s considered “hot” for other cars (230* F). 

Many early turbo BMW E82, E90, E92 and E93 models have an oil cooler that’s simply too small for the job – if they have one at all. In fact, in 2006, the 335i did not even have an oil cooler! This is why if you do any of spirited driving at all or just want to extend the life of your motor, you should install an oil cooler large enough to sufficiently cool the oil, keeping your engine running cool and happy. You can read more about why your N54 Engine Needs an Oil Cooler, and how badly it’s needed HERE.

Consider adding an oil cooler, such as the ones offered by Evolution Racewerks to keep your BMW’s oil cool and lubricating your motor like it should be to ensure many happy miles to come.

*Evolution Racewerks Sport/Competition Series Oil Cooler 135i/335i
At BMW N54 Mods to get the most out of your N54 Twin Turbo six. If you have questions about modding your BMW N54, don’t hesitate to consult our friendly and experienced Modification Experts, who can fill you in on what a particular mod will do and point you in the right direction of making a mod you’ll love – call us at 714-582-3330 today, or email us at sales@modbargains.com.

We hope this information is helpful to you – enthusiast to enthusiast- so that you can enjoy your turbocharged BMW 335i to the fullest and get more smiles-per-mile from your Ultimate Driving Machine.

Story by Nicholas Gregson in collaboration with Senior Modification Expert Alan Wei
Other Great N54-Related Tech Articles:

Why your N54 Needs A BOV & Chargepipe Upgrade – 29Ft/LB Power LOSS!

Why your N54 Needs an Oil Cooler

Meth Head: Go Faster with Methanol Injection on your N54