GrimmSpeed Unequal Length Header for your Subaru 04-21 STI and 02-14 WRX. Fitment: 2004-2021 Subaru STI 2008-2014 Subaru WRX 2002-2005 Subaru WRX 5MT (Requires STI Oil Pan and Pickup) 2006-2007 Subaru WRX (Requires STI Oil Cooler and Feed Pipe) Quick Specs: Innovative 1.5 to 1 Unequal Length Runners - Each bank of runners is equal length, allowing for equal length performance with an unequal length sound 4-into-1 Low-Angle Merge Cast Collector - Ensure minimal restriction and maximum performance Smooth, Restriction-Free Flow Throughout – Single piece mandrel bent tubing welded to a single piece merge collector removes unwanted “steps” Substantial Power/Torque Gains - +25hp and +25ft/lbs of torque over stock Quickest Spooling Aftermarket Header - Faster spool and more power compared to the competition No Tune Required – Safe to run, just bolt on Gaskets and Hardware Included – Everything you need to get installed and on the road Designed To Fit With Aftermarket Oil Pans - Fits with the STI oil pan or popular aftermarket options Full 304 Stainless Steel Construction - 1/2" flanges and 14ga runners for extreme durability Manufactured and Welded In The USA