Mishimoto is proud to release the Performance Cat-back for the 2015+ Subaru WRX/STI. The biggest complaint is the stock cat-back exhaust systems lack of aggressiveness. By installing the Mishimoto Performance Stainless Steel Cat-back, the exhaust system is able to breathe easier, providing horsepower, torque, and a rich exhaust tone. After comparing many different muffler sizes and designs, the Engineers at Mishimoto chose oval mufflers which prevent highway drone, but still provide an aggressive exhaust tone. During dyno pulls with the 2015 WRX w/ CVT, Mishimoto saw gains of up to 9 whp and 8 wtq using 93 octane fuel while maintaining safe AFRs on a stock tune (see additional images for dyno chart). This exhaust installs in under one hour and features quad 3.5 staggered double wall polished tips. The Mishimoto Performance Cat-back Exhaust provides an extremely aggressive turbo and exhaust tone under acceleration and boost, giving you that aggressive tone you have been looking for! The engineers at Mishimoto designed this cat-back as a four-piece design with precision TIG welded 304 Stainless Steel. This allows a smooth exhaust flow from the 3.0 2-bolt exhaust flange all the way through the 2.25 y-section. To top it off, this cat-back includes two 2.25 V-Band clamps, a 3 exhaust band clamp, a new 3 2-bolt flange gasket, and all stainless steel hardware, so you dont have to worry about your hardware rusting ever again! For 2015 WRX owners looking to get the most out of their WRX, this cat-back exhaust mates perfectly with the Mishimoto Performance Downpipe. The Mishimoto Cat-Back Exhaust is proudly made in the USA and comes with the Mishimoto Lifetime Warranty you know and trust.