Vacuum exhaust valves allow mild sounds while streeting, and roaring exhaust sounds on the track.A valve can open and close the exhaust flow. Examples of use are a screamer pipe directly after the downpipe, or a muffler bypass.
Exhaust reducers in stainless or mild steel.Models with three diameters can be cut to fit a pipe with the middle diameter as well.An exhaust pipe reducer allows a diameter change with minimal flow restrictions.