4 - inch stainless constant - diameter cat - back pipes and straight - thru muffler dramatically improve flow up to 122 and lower EGTs. Virtually eliminates backpressure, rich, throaty sound. Formed of stainless, heavy - wall tubing with constant - diameter bends to maximize airflow and lower exhaust gas temps. Banks replaces the factory's restrictive muffler with a polished - stainless Monster muffler featuring a straight - through 4 - inch diameter path that flows up to 129 better than stock. The Banks - designed expansion chamber dissipates the annoying mid - range exhaust drone that accompanies most straight - through mufflers. Monster muffler utilizes spun ceramic, very - high - temperature packing, and delivers an authoritative - - but never intrusive - - exhaust sound. And the 5 - inch polished rolled - edge tip has an adjustable clamp for positioning on the tailpipe. Get it in your choice of chrome - over stainless or high temp black (And to help keep it looking good, there's a 12 inch air gap to keep heat from tarnishing the finish.)