Another vote for the Anderson Power Pipe. Steve @ Houston Performance dynoed an 01 cobra picked up 10 hp with stock mass air. I already had the UPR pipe or I would have one on my car right now. With the Anderson pipe it relocates the meter in the fender so you don't have that bend right in front of the meter like you will with the densecharger or WMS. Some say the turn in front of the meter causes the idle problems. I have the mac cold air on my other car ( i did not know any better when I bought it ) and do not have idle issues, but I think it's different from car to car.