My IAT's are fantastic on my car using the stock heat exchanger.

Just read up on the results people have with their mods and spend your money wisely. There are a lot of parts out there that are hype and give little to no results and there are parts out there that are a big bang for the buck if you just pay attention. You can be moderately fast for a bunch of money or be faster than most for a much more reasonable amount of money.