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E88 Turner Motorsport Performance Exhausts

E88 Turner Motorsport Performance Exhausts Turner Motorsport has been tuning BMWs since 1993 and exhaust upgrades for BMW are one of our favorite modifications. Performance mufflers, headers, resonator-delete, muffler-delete, race exhaust, and other exhaust upgrades have all been a part of our tuning outline since the beginning. Upgraded exhausts have multiple benefits: better sound, lighter weight, and power and torque gains. Although we sell multiple exhaust product lines (Borla, Corsa, Supersprint, Akrapovic, and others) there are times when we desire something unique and different. These exhausts are our own design with concept and engineering done by our own designers and staff and then trial-tested on our project and employee cars to ensure our design objectives are met.
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Factory downpipes and their catalysts are a choke point for exhaust gases. This restriction slows turbocharger spool and reduces efficiency, and has a significant impact on power. When modifying their N54, most enthusiasts quickly find OEM downpipes offer insufficient performance as power levels are increased, resulting in disappointing results from other modifications. While some find catless downpipes to be the answer, their benefits are increasingly failing to outweigh the downsides when used on the street. Exhaust volume is increased (combined with a full exhaust may be too much for sensitive ears), check engine lights are frequently illuminated, and emissions are greatly increased (a problem for the environment and in passing emissions testing).

Turner engineers designed downpipes that met a happy compromise - excellent flow with high performance 48-state legal catalytic converters. By utilizing cats, these downpipes offer much lower emissions than catless products (and in many cases, no check engine light), with little sacrifice to performance versus their catless counterparts. These high-flow units feature a 3" inlet, followed by a series of smooth radius bends and efficient catalyst, exits as a 2.5" to retain compatibility with popular cat-back exhausts (as well as factory exhaust piping).

We confirmed power and efficiency improvements are present on both a stock tune with even greater power to be found versus factory downpipes while utilizing a simple ECU tune. These gains were confirmed on our in-house Mustang AWD-500 dynamometer while running an off-the-shelf (no tuning trickery in these numbers) Cobb Stage 1 tune:

Stock downpipes wheel horsepower: 314hp @ 5700rpm
Stock downpipes wheel torque: 386ft/lb @ 4000rpm

Turner downpipe wheel horsepower: 334hp @ 6000rpm
Turner downpipe wheel torque: 390ft/lb @ 4100rpm

Max gains:
 @ 6500rpm
23ft/lb @ 6000rpm

Product features:

  • Large diameter 3" tubing and 200 cell high-flow catalytic converters - significantly reducing flow restriction found on factory downpipes
  • 304 stainless steel with beautiful quality TIG welds
  • Precise fitment - no wrestling to install, listening to clunks, or feeling vibration associated with ill-fitting downpipes
  • Uses factory clamp 11657620508 and factory gaskets 18307553601 (x2) and 18307553603 (x2). Install kit available here

Looking for even more power? Our knowledgeable sales staff is eager to help with your build - give us a call.

This item fits the following left-hand-drive BMWs with the N54 engine:
2008-2010 E82 BMW 135i 1M Coupe
2006-2010 E90 BMW 335i 335xi 335i xDrive - Sedan
2007-2010 E92 BMW 335i 335is 335xi 335i xDrive - Coupe
2007-2010 E93 BMW 335i - Convertible


Turner Motorsport
Part #: 000932TMS
Price: $870.90 (USD) 
In Stock
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