S55 F80/F82/F87 M3, M4 and M2 Competition which are one of the only downpipes to feature a cast stainless steel v-band to pipe transition. These 3″ downpipes are the best bang for the buck mod available for your S55, with gains from 25hp & 30tq when tuned. By eliminating the restrictive catalytic converters in the factory downpipes, back pressure is reduced significantly which results in faster spool, an increase in power & a more aggressive exhaust note.