I certainly did not notice any power increase. I don't doubt 3-5 hp on the top, and real gains with a good exhaust, but I didn't notice it. I did notice improved throttle response. I have a Demon-style heatshield that closes off the whole side of the engine bay where the airbox and battery used to be. With a much larger air mass to suck in when the throttle plate is cracked, I get more instant-on power. It's small, but definetly perceptible. At the first autocross with the intake, I had to modulate the pedal just a tiny bit more than before to avoid spinning on corner exit. However, if I didn't have a lot of seat time in this car flicking the throttle open and shut around tight courses, it wouldn't be too obvious. The difference I get when the air cools down in the fall is much more noticeable, both in power and response. What I did notice, along with everyone else, was the sound. I had a co-driver, and as he came by my worker station into a sweeper, the car just roared like never before. It sounds very healthy and powerful, not raw. So power, maybe; throttle response, yes; noise, oh my my!
