MITSUBISHI SS 3" DOWNPIPE EVO X 2008-2015, RALLIART 2009-2015MFG# 552210 DESCRIPTION The trailing end flange uses the stock donut gasket and factory spring bolts to aid in flex, longevity and proper fitment. A bespoke cast 3" flat flange provides a true mating surface at the O2 housing. These features provide an improved seal compared to other methods, as well as reduced noise. WHY? The COBB Tuning Mitsubishi Downpipe features a widened diameter of 3" for increased flow of exhaust gases from the turbo charger