By BMWs sound metal. They always have, and probably always will. Custom exhausts take that sound and crank it up anywhere from about 11 to too-many notches, so you need to be aware of what you’re getting yourself into– you don’t want to put a pipe on your ultimate driving machine and have to suffer (or make the neighbors suffer) very time you drive it. No matter which exhaust you pick, however, they still sound like they’re ready to tackle anything from Angeles Crest Highway to the Nurburgring any day of the week.
The new 3 series underwent a split in the early 20-teens: four doors stayed the BMW 3 series and two door coupes became the BMW 4 series. On top of that, there are a half dozen different engine options for these cars thanks to a mid-cycle refresh, and even more outside of the US. Fortunately, if you’re planning on upgrading your new BMW 3 or 4 series, modifications are pretty similar between the two, and aftermarket manufacturers have responded quickly to model year changes. Here, we’ve got some recommendations for custom cat back exhausts for F30/F32 series BMWs, separated by class.
320i/420i
The basic model BMW ¾ series come with 2.0-liter turbocharged 4 cylinder engines. In the early days, this option was the N20B20; in 2016, this changed to their new architecture, the B48B20A. Both of these engines should be capable of attaching to the same cat-back exhaust options. For a bolt-on upgrade, Magnaflow makes a Street Series cat-back exhaust system that offers better flow and a slight volume increase without getting too complicated. Unfortunately, if you’re looking to upgrade further, you may have to improvise slightly; the good news is that a ¾28i or ¾30i cat back options will bolt in as well, the bad news is you’ll also need to figure out how to fit a twin-pipe system in past the stock bumper. Either cutting or an aftermarket exhaust will be necessary.
330i/430i
Speaking of which, there are plenty of cat back options for the ¾30i! Remus makes a solid starter upgrade for your vehicle. Remus’s cat back/axle back systems give a volume bump from stock and makes the characteristic DSG farts (Google “DSG farts” if you don’t know what we’re talking about, it’s pretty great) much louder. Oddly enough, it seems to sound a little bit like half of an F10 BMW M5. Going beyond that, Armytrix is here to wake up your neighbors with their Valvetronic exhaust. With the valves closed, it’s a pretty solid contender in the “mild” upgrade category. With the valves open, it’s a dead ringer for the sound of a group B rally supercar.
335i/435i
This is where it goes from “hey, that’s pretty fun” to “woah crap that’s fast!” Bmw’s N54 inline-6 engines made waves in the euro tuning scene in the late 2000s, with modifications bringing tons of extra horsepower out of the twin-turbo powerhouse. The N55 follows suit, switching to a single twin-scroll turbo for a smoother powerband. The two easiest ways to get power out of an N55 are a tune and an exhaust; for the second one of those, we’ve got you covered.
The aFe Mach Force Xp cat back for the ¾35i is a twin exit system that provides a 12hp/10lb-ft bump over stock, thanks to a non-resonated midpipe and larger outlet piping. This follows the trend of “louder but not obnoxious” set by the Remus cat back built for the ¾30i. The “louder still and a little bit obnoxious” counterpart to this is the Borla ATAK cat back. Borla offers straight-through mufflers and resonators to give you a sound that’s loud, angry, and proud of it. The Borla ATAK exhaust sounds much like the BMW M2, harkening back to the earlier days of BMW turbo-sixes.
340i/440i
If you’ve been following anything along the lines of the 2020 Supra, you’ll recognize the moniker “B58.” The B58B30 twin-scroll turbo inline 6 replaced the N55 in 2016, and offered more horsepower and reliability out of the gate. The engine upgrade resulted in a change in model designation from ¾35i to ¾40i. There’s still room for improvement though: like on the N55, aFe makes a Mach Force Xp cat back for the B58. This new generation doesn’t get quite as much power out of a new exhaust, but makes just as much noise as well as some fun pops and burbles on overrun. If you really like pops and burbles, there are few better places to look than AWE Performance’s Exhaust Suite. It goes from “man, that sounds pretty good” to “HOLY WOW I CAN’T HEAR YOU OVER MY AWESOME RACECAR SOUNDS” at the push of a button, thanks to retention of BMW’s stock exhaust mode valving system.
M3/M4
So BMW went out of their way to make this revolutionary new engine (the N55) and made it sound loud. Super loud. Some say they were trying to make it sound like the older, naturally aspirated inline 6’s in the E46 and E36 M3, and the M-sport exhaust ended up making it loud. Not necessarily good, just loud. Here are some options to make your BMW M3/M4 sound… different.
Yet again, we start with the Borla ATAK system. It’s still loud, but it’s loudness with direction. This system eschews pops and bangs for old-timey refinement. For a similar option, check out the Dinan exhaust system for the M3 and M4. It’s pricier, but Dinan has a historic tradition for modifying and tuning BMW vehicles. To go full racecar with your M-Performance special, get exotic and check out Akrapovic’s cat back for the M3 and M4. This multi-part system takes the stock exhaust’s tones and turns everything up to 11, adding a ton of deep gurgle at idle and low revs and shrieking highs at the redline.
Now, a cat back is a great start. Above all, they make things sound freer and generally better than stock. To get real power out of a BMW turbo engine these days, we recommend an intake and downpipe set to go with any of the exhausts mentioned here. Check out the Motoroso Marketplace for cat backs and more for your BMW!
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