I can telly uo from a professional stand point, and has been proven on my dyno, a home made intake will actually hurt your performance. I had V6 mustangs, Neons, RSX, etc..... come up there and they tried the cheap way out. Its not worth it. they lost 4 MPG and most lost 6 RWHP. If it was possible to make your own and be as good as lets say C&L or K&N, then they wouldn't be in business. On my Mach 1 i actually seen a very nice gian on the K&N setup of 12.3 RWHP. Most cars are lucky to get at the most 6 RWHP. your 4 cylinders will not get much at all, it may help throttle response thats about it. V6 import it helps a little better, and same as domestic, but if you dont have 8 or more cylinders, its best for you to buy a replacement filter thats not foam and you will see about the same increase in power. If you want quaick HP go with a performance chip. DO NOT go with hypertech. Most of the time they will screw your ****** up. Superchips or SCT only way to go.