The new and improved Perrin Sectional Catted Downpipe System utilizes 49-state* legal catalysts! Perrin has released the new two-piece downpipe for the Subaru WRX, STi and Forester XT so you can just replace the section with a fried catalyst and/or build the system as you can afford to. Performance gains will be comparable to a catless downpipe as the high-flow catalysts in the Perrin WRX/STi two-piece downpipe are extremely non-restrictive. The Perrin two-piece downpipe for the WRX, STi and Forester XT is perfect for those looking for performance gains similar to a catless downpipe, but need to keep catalysts in the system due to emission, tuning and racing specifications. Some of the main features of the Perrin Sectional Catted Downpipe for the WRX, STi and Forester XT include 3" polished 304 stainless steel piping with a wastegate diverter. The wastegate diverter separates unused exhaust gases from the exhaust stream and then channels them back into the system further down the line to reduce turbulence. The result is smooth, maximized exhaust flow -- which is a necessity for your turbocharged Subaru's performance. The WRX/STi/FXT stock downpipe (and some less expensive aftermarket units) have a flat flange at the turbo housing that makes no provisions for the wastegate, resulting in exhaust backing up into the turbo and slowing spool up. Another feature of Perrin's WRX/STi/FXT Sectional Catted Downpipe are 1/2" flanges, which eliminate warping and leaking under high temperatures. Perrin backs their downpipes and catalysts with a limited warranty. This downpipe will attach to any cat-back exhaust system, including stock.