ive just purchased a 04 mach1 auto trans,deff doing a cat back,at what power level should i go with a 1-5/8 long tube(pain in the butt install)or a shorty,ive heard decent things about the stock manifolds as well,i would really like to go with the kooks long tubes and there cat x-pipe,are shorty's worth it on a stock engine?if im going to spend 5-600 bucks on shorty's and go thrue the hassle just as well spend the extra 500 and go long tubes with the hassle.just lokking for some info.