N20 Downpipe Catless Downpipe CenCalUpgrade to the CenCal BMW N20 catless 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 N20 with stock turbo, even more on cars with upgraded turbo. The flex pipe section will help reduce the stress and unwanted vibration caused by heat