I'm fixen to complete my build up, need help on a couple things. I have to replace the head on my car so I was thinking of getting the bullfrog head package, I wasn't going to get the cams springs and valves. just woundering if anyone knew anything bad about their heads. I'm getting a set of SRP .020 pistons, I had red somewhere that when your running turbo pistons that they expand, and when the car is cold they make a knocking sound almost like a diesel. it's suppose to stop when car warms up I guess. I've heard people say theirs don't stop, I was woundering if someone could explain this to me. Is there a way to minimize this or is it something that you have to deal with?