Originally Posted by Psychopete
Actually, a badly set up CAI has more opportunity to suck in more "bad stuff" than the stock system. They usually set near the cooling fan under the hood. I see a lot of CAI setups that are very counter intuitive over what the factory has put in (but I won't hate on it, all in learning and fun). But from what I have gathered, it appears that any gains from a CAI on a stock engine are very small and (are at RPMs mostly never used or are unsafe for the engine).
Your right, if you look on k&n's website, they have the horsepower gains for your truck, and most all rangers horsepower gains with the CAI are around 5000 rpm's which means you basically have to hold it till you hit the rev limiter to get any horsepower gain, which is not good on your engine.