stock vs shorty vs long tube

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.

Shorties net you almost nothing over stock manifolds (only improvement is on top and that's only around 5 hp). Go with long tubes and set aside a lot of time to install them. Remember, either pull the engine or drop the k-member to install either or since it's impossible otherwise.

definately long tube. i hate my shortys but dont want to $$$$ to take em off and $$$$ to put on the longs after $$$ to buy em. i went cheap and regret it