VRSF Race Downpipe BMW X3 X4 35i N55 F25 F26 BrushedVRSF Race Downpipe BMW X3 X4 35i N55 F25 F26 (Brushed) The factory downpipe on the N55 X3 and X4 is the single best bolt on upgrade available. By eliminating the restrictive catalytic converter and reducing back pressure, the VRSF 3. 5" Race Downpipe delivers faster spool, 20 25 horsepower gains with a tune, and a more aggressive exhaust note. Direct bolt on fitment, no cutting required. Fits both RHD and LHD models. Note: This downpipe fits PWG