2011-2012 BMW 135i/335i N55 Downpipe
Our downpipe is made from T-304 Stainless Steel, which is then polished. It mates to the factory twin-scroll turbo with all stock hardware and mounting points. Unlike our competitors, we manufacture our downpipe in the USA (Arizona).
Interior dimensions are 4" at the turbo with a smooth transition to dual 2.5" flanges at the exhaust mounting point. Extra thick flanges are used on the exhaust mounting side to ensure there will be no warping or exhaust leaks. Additionally, we use reinforced hangars to keep everything tight and sturdy.
Finally, we include 2 threaded bungs for you to reuse both of the factory oxygen sensors, so there is nothing "extra" left uninstalled.
On a stock car, our downpipe has shown +25hp and +12lb/ft peak numbers on a DynoDynamics dyno in 90 degree weather. However, from 3900rpm - 6000rpm, we saw an average of +37hp and +32lb/ft. This means that in the "meat" of the RPM range, you'll really feel it in the "butt-dyno." We recommend pairing the downpipe with a JB4 tuner for the ultimate in performance.
Like all Shifteck parts, this downpipe includes a lifetime warranty against any defects in product workmanship.