N54 Downpipes
Advanced Flow Engineering MSRP: $749
Info: afepower.com
With the popularity of the N54 3.0L twin-turbo motor found in the BMW 135i and 335i, aFe decided to develop new Race downpipes that are claimed to unlock 28hp and 28 lb-ft. The high-flow pipes ditch the cats, so it won’t be street-legal but they’re made from TIG-welded 2.75" 304-stainless steel. They also have 3/8" flanges for a leak-free seal and a factory-like fit.