This is the pinnacle of induction systems for the Subaru WRX/STI range. The plenum volume and runner length combination has been optimized for brutal low and mid range torque while increasing top end power aggressively. We've had customers pull off other aftermarket intake manifold systems to install this as performance is unmatched. Gains on even a stock setup are quite high at 10%+ however we recommend the Track version manifold for any performance setup not requiring AC up to the most extreme track and drag cars. For cars requiring even more power in the upper rev range the track version can be supplied with shorter billet TGV's (lower runner section).