Picking up where we left off with Part I of our rundown of the Best Bolt On Mods for BMW F30 328i (and 220i/228i/320i/428i), we talked about the intake system, tuning and intercoolers. In part II, we’ll be discussing how to pull more power out of the car’s exhaust system.

Let your N20 Breathe Freely With A Performance Downpipe

One of the biggest Bang-For-The-Buck upgrades for turbo engines, including your 328i is a high performance BMW N20 downpipe.  When it comes to downpipes, you have a choice to make: Catted, or De-Catted. This is a big decision, because, OK, yes, a catless downpipe makes more power overall and is cheaper – but there’s a tradeoff to that.

About Catless
A catless downpipe will almost always cause a Check Engine Light without a tune to match, and whenever you’re stopped at a red light you’re going to smell that unburnt fuel – not to mention that a catless downpipe is illegal for street use in all 50 states these days. How much the smell bothers you and your passengers is a key factor to consider before making your decision. Is this your “weekend” car, or do you drive your kids and spouse around often in it?

About Catted
On the other hand, a Catted Downpipe won’t smell, makes slightly less power than catless and costs more – but there’s a reason for that. Usually a catted downpipe has a 200-CPSI (Cells Per Square Inch) “Sport” Catalytic converter – and no, unless otherwise noted, none are CARB legal in California, but the vast majority of catted downpipes are 49-state legal for street use. Catalytic converters, even low-density sports cats, are expensive for a reason. Every catalytic converter is filled with a good bit of rare-earth metals like platinum, gold and other expensive heavy metals – this is why a few years back thieves were stealing the catalysts from Toyota 4runners due to the extremely high “scrap” value. Catted downpipes typically do not cause a check engine light with the stock tune (though this can still happen), and the catalyst keeps the car a little quieter and keeps the car from smelling like gas, and you’re 49-state street legal.

 

CATTED DOWNPIPES for BMW N20 Engines

Evolution Racewerks Competition Catted Downpipe for N20 like their catless system, is specifically designed for a smooth HP and torque increase across the powerband. Featuring 4″ piping as well, this catted downpipe offers a gain of +13whp and 24wtq, and its catted design offers an HP peak that’s higher up in the rev band for a more balanced downpipe. This ER downpipe doesn’t specify whether or not it can cause a CEL, so to err on the safe side we’d still advise using it with a tune – which again, you want to do anyway to reap the maximum benefit of a performance downpipe. These downpipes are available in standard finish as well as a black ceramic high heat coating for a stealthy look.

Then we have this BMW N20 328i catted downpipe from Remus Exhaust. The Remus system increases power by 13whp/8wtq, but that’s quite conservative and the tradeoff is EEC-approved, so as to not cause a check engine light and features the same high standard of quality you can expect from a REMUS Exhaust system. This means you’ve got a high performance cat that works together with the stock ECM and even better with a tune (of course). Remus put together this video that shows it off better than a photo can.

Last but not least is Wagner Tuning’s Catted Downpipe for BMW N20 Engines – including BMW F30 328i. This is a brand new item from Wagner Tuning and fits most late model N20 engine applications, as well as the F30. This high quality cat is a direct replacement for the OEM BMW Catalytic Converter and like the others, also features a 200CPSI sport cat. This design reduces backpressure and offers OEM-level, perfect fitment for a straightforward bolt-in installation. The gains aren’t yet well documented, but it’s reasonable to expect 10-13whp or so without a tune, and like the Remus catted downpipe, the Wagner Tuning N20 Catted Downpipe WILL NOT cause a check engine light.

Now here’s where we can’t help you so much, because this next part is kinda subjective. When you go to Baskin Robbins, the server cannot decide what your favorite flavor ice cream is for you, much like you and I might have different tastes in music. Preferences for exhaust sound work the same way, and like Baskin Robbins has at least 31 flavors, tastes in exhaust sound are just as diverse.

You see, an exhaust system is really important because it is something that can really drive you nuts if you pick a system you don’t end up actually liking. Just because I like a wake-the-neighbors racecar exhaust doesn’t mean it’s a good idea if your HOA already doesn’t like you or if you don’t like drone or noise. The best exhaust for one guy may not be the best exhaust for you, and that’s why it’s important you listen and decide for yourself what sound you like. If you still have questions or are unsure about something, you can always call our Modification Experts for Advice at 714-582-3330 A performance exhaust system will help wake your N20 or N26 up a little bit more, and complements what you’ve already started with a performance downpipe and tune. 

 

Active Autowerke’s Axle-Back exhaust system for BMW F30 328i alone is good for a dyno-proven gain of +9rwhp and +13wtq, your choice of dual round or single oval tip design utilizing the OEM driver’s side exit configuration. The exhaust note is on the more aggressive side, but take a listen to the Youtube video and decide for yourself whether the sound is right to your ears.

 

For those who are concerned about their warranty or accept only OEM BMW Performance Parts, this BMW Performance Exhaust System for F30 BMW 328i is a great option and offers some HP and TQ gains (though how much is uncertain) and it is almost certainly the mildest exhaust of the bunch – it’s louder than OEM, but doesn’t go overboard and features dual 80mm tips engraved with the ///M logo.

Then you have the Eisenmann Race Exhaust for the F30 328i, offering a great muscular burble, it’s going to be on the louder side of the spectrum. Available in Axle-Back or cat-back configurations as well as single-exit w/dual tips or dual-exit w/quad tips to suit your style and taste, this system is ideal for someone who wants to be heard. No dyno sheets available as of press time, but you have to imagine in cat-back configuration, gains will probably be similar to other N20 catbacks.

 

 

 

And last but not least is this Remus Cat-Back Exhaust for BMW N20 328i / 428i, the Remus Axle-back for 328i alone yields +3rwhp / +5wtq, but as of press time we don’t have dyno figures for the Cat-Back configuration. What we can tell you is you’ll get a sportier, euro sound and OEM-quality exhaust components when you choose a Remus exhaust system.

All told, if you add up the gains and went full-bolt on with your upgrades, your 328i or 428i will be looking at a massive increase of +100whp and +120+wtq if you went full bolt on with an Intake, TB Spacer, Intercooler, Chargepipe, Downpipe, Cat-Back Exhaust and Tuner Module. Remember, these upgrades work best as a complete system and should be looked at as one mod supporting the other – your intercooler helps support your tune, intake and downpipe, the chargepipes help your intercooler, intake and turbo, your intake helps the intercooler, the TB spacer helps all of these things, the downpipe helps the turbo and the tune helps you get the most out of your downpipe and intercooler- like a spiders web, it’s all interconnected.
If you have questions about modifying your N20 engine or just don’t know where to start, we invite you to chat with our friendly and enthusiastic Modification Experts at 714-582-3330 or email us at [email protected] and our experts will get back to you right away.

Thanks for reading – Click here to revisit Best N20 Bolt On Mods Part I – Intakes & Performance Tuning for BMW F30 328i with N20 or N26 engines.

If you have questions about upgrading your BMW F30 328iBMW F32 428iF22 228i or F10 528i, we invite you to talk to the Modification Experts. Call our BMW specialist Alan Wei directly at 714-582-3330 x8006 or chat live with the Mod Experts at ModBargains.com or just give us a call at 714-582-3330 and any of our experts can help you make an informed purchasing decision so that you can trust that you’ll be totally happy with the upgrade you’re about to drop some cash on and don’t end up with a part you don’t like.

Story by Nicholas Gregson in collaboration with Sr. BMW Modification Expert Alan Wei