Upgrade from the stock N20 downpipe to the MAD N20 4" catless downpipe for maximum airflow, power, and sound! Upgrade to the MAD BMW N20 4" downpipe to eliminate the backpressure caused by your stock catalytic converters. By upgrading to our downpipe, your turbo can now spool faster and achieve maximum power. As a bonus, your car will sound a lot nicer as well. Expect up to a 30HP increase on a tuned BMW N20with stock turbo, even more on cars with upgraded turbo. The flex pipe Section will help reduce the stress and unwanted vibration caused by heat and engine Movement.  Features: Smooth bends for maximum airflow without any drone Up to 30HP increase on the stock turbos, even more on upgraded turbos Lifetime warranty on defects and fitment 90 day return period All orders ship in 1-2 business days   Fitment: Fits N20 engines only, please check your car and confirm that it has the N20 engine before placing an order. 2014-2016 228i 2012-2015 328i  & Xdrive (F chassis) 2014-2016 428i & Xdrive 2012-2016 F10 528 & Xdrive  If you are having issues with the downpipe fitting with the stock bracket, please remove the stock bracket