The thing is, logically it makes more horsepower. More air/colder air increases hp. Now, the thing is, how much more air flow does this give over the stock piece? Maybe not a ton, but some. Honestly I don't believe that a CAI really makes it's peak power until it's actually moving, thus this can't really be proven on a dyno. However something most everyone says is that the throttle response is alittle quicker which is nice. The reason why most people don't get one is because for 200+ dollars it's biggest pro is that it looks cooler, and the only people that will notice are at a car show, and IMO a CAI doesn't have anywhere near the same appeal as seeing a blower in the engine. An exhaust may not yield much more hp then a CAI, but atleast you are getting a noticeable sound and sometimes a better looking exhaust out back. CAI's are definately not a bad mod, but not going to give the instant gratification like for instance a gear swap would.