4 - inch constant - diameter pipes with Straight - thru muffler. Cuts back pressure up to 81 Percent. Turbo Back System with 5 - inch Chrome tip. Includes Power Elbow. EXCURSIONS Banks 4 inch Monster turbo - back stainless steel exhaust features streamlined turbine - outlet pipe, intermediate pipe and tailpipe all formed of stainless, heavy - wall tubing with constant - diameter bends to maximize flow, lower exhaust gas temps and slash backpressure up to 81 percent. (Available with or without a cast, large - bore Power Elbow housing.). The polished - stainless Monster muffler features a straight - through 4 inch diameter flow - path with a Banks - designed expansion chamber to dissipate the annoying mid - range exhaust drone that affects most straight - through designs. The muffler utilizes spun ceramic, very - high - temperature packing, more than doubles stock exhaust flow, and delivers an authoritative - but never intrusive - exhaust sound. And the 5 inch polished rolled - edge tip has an adjustable clamp for positioning on 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.).