I would like to get a FLowmaster cat back system and I was going to start calling around but before I do I am wondering which stage of Flowmaster to use stage 1, 2 , or 3? The stang is a daily driver, not really racing and dont really want too much noise. Are there any significant gains in HP from which stage. ALso I DO NO WANT TO VOID THE WARRANTY. Any help would be greatly appreciated. thanks