Take the restriction out of your N55 with the OneFastShop 3.5 inch catless downpipe. The factory catalytic converter sits right off the turbo and is the single biggest choke point in the exhaust - removing it frees up real power, spools the turbo sooner, and opens up the deeper note the N55 was built to make. Designed for early production F30 335i and F20/F21 M135i with the pneumatic wastegate (PWG) N55 turbo, built 2012 to mid 2013.
Expect +20 to +25 horsepower with a supporting tune (more on upgraded turbos), faster spool, and sharper throttle response. It's a direct bolt-on with no cutting required, works with OEM and aftermarket cat-back exhausts, and is backed by a lifetime warranty on defects.
| Diameter | 3.5 inch (full diameter from turbo outlet) |
| Material | 304 grade stainless steel, mandrel bent |
| Flanges | CNC machined billet |
| Welding | Hand TIG welded |
| Mounting | Welded bracket included |
| Configuration | Catless (race), catalytic converter removed |
| Engine | BMW N55 PWG (pneumatic wastegate, early production) |
Wastegate type: This downpipe fits early production N55 engines with the pneumatic wastegate (PWG) turbo only - F30 335i and F20/F21 M135i built up to July 2013. PWG turbos use a vacuum line and diaphragm. After July 2013 BMW switched to the electronic wastegate (EWG) on these chassis. If your build date is after 07/2013, you likely have an EWG turbo and need our N55 EWG 4 inch downpipe instead - verify your turbo type before purchase.
Gasket required: A turbo-to-downpipe gasket is required to seal the downpipe to your factory turbo. Our 3.5 Inch Turbo to Downpipe Gasket for BMW N55 is sold separately - add one to your order.
Tuning & check engine light: Removing the cat means the rear O2 sensor will eventually set a check engine light (a catalyst efficiency code such as P0420) on an otherwise stock car. This is normal for any catless downpipe and not a fault with the part. To run it correctly and keep the light off, the car should be tuned with the rear O2 sensor turned off - any major N55 tuning platform supports this. We strongly recommend installing this downpipe with a supporting tune rather than on a stock vehicle.
Off-road use: Intended for off-road and track use only. Not legal for use on public roads and may not comply with emissions regulations. Check local laws before installation.
| Year | Make | Model | Submodel | Engine |
|---|---|---|---|---|
| 2012-2013 | BMW | 3 Series | 335i / 335i xDrive (F30/F31, build date up to 07/2013) | N55 PWG |
| 2012-2013 | BMW | 1 Series | M135i / M135i xDrive (F20/F21, build date up to 07/2013) | N55 PWG |
