Which has better HP/TQ gain between cat-back exhaust or Header with one-ball & hi-flow cat?

 

Cat-back and header.

-Cody

 

I see by your mod list you already have the one-ball, so go ahead and get the header done. If you want to squeeze a bit more out of it, get it ceramic coated by a machine shop and weld it onto the stock cat for a not-too-expensive mod ($500 for the obx header + head coating + install).