exhaust questions

OK so im a little confused on what to do for exhaust. I know that yall have talked about it a million times but if you dont mind could you please do it one more time for me. Ive been reading over the debate over cat back or just a muffler and i dont know what to do. Thermal is gonna be coming out with there exhaust in a week or so but im a little concerned about losing torque or HP. Everyone who has just a muffler or the Stillen rear section seems to be happy, but so are the people with custom catback or the stromung. When my guy talked to the Stillen rep. he said they lost power on their catback system, and im wondering if once i put headers on it will that even out the flow so where it would be better to have catback. I dont know i would appreciate a little help though.

02 black Spec Injen CAI, Eibach pro kit,(exhaust in a week or 2).

personally, if i were to do it again, i would get a catback system. these systems are after all madrel bent. the factory piping is also very small and seems to be restrictive. i have never heard of a catback making a car lose horsepower but if the stillen rep says so, then i have no idea. i have a universal muffler and can say that i like it, but i think i would be happier with a catback system