Question, did you have just a stock paper air filter? aka a fram, stp etc paper filter or a "performance" drop in like k and n and aem and spectre etc make before doing this? I ask because I am interested in doing a CAI if it is worth the investment. I had the stock like paper one the dealer I bought mine used from put in when I bought the car (they had done oil change, filters and tires, the tires where cheap and I feel it all was but that's another story...) anyways like you I wanted more power and I put drop in k and n filters in all my cars anyways as they last longer then a paper filter would between cleaning (paper ones obviously cant be cleaned) and save money in the long run as I can clean my k and n drop in 3-5x with one $10 cleaning kit doing it once a year instead of needing a new paper one every 6 months or so. But I also ask because I notice a pick up in power from 3,000-5,000rpm (I have a 2011 2.5L hatch) with the k and n versus the paper ones. would you say its very noticeable or just slightly? mine seems to just be a hair more then slight as I can feel it needs less throttle to go with the k and n and once up in speed shifts better (mines an auto, I know could not find any manuals in buyable condition around when I needed a car) it also lets it go slightly higher in speed before the stupid governor kicks in. with the paper 116ish was when the governor kicked in but with the k and n its slightly after 120mph (the 2.5 could easily go 145 before redline if they would let it, dibbling the governor in the gen 1 was easy all you had to do was take out the abs fuse, maybe same here) my old 08 manual 2.3 hatch would cut at 120ish with the governor active(same drop in ka nd n did same to this car) if I removed the abs fuse it would go to redline and hit about 142mph and bounce the tach not bad for a small 4 cylinder hatch n/a motor. anyways would you say its more noticeable then my description with the drop in or about the same?