The problem is that you dont significantly gain anything because you are not changing the valvetrain so youre still going to start boost stacking when you increase boost. The U bend is more of a restriction than the stock cat. If you want to remove it thats fine. No one is telling you not to. But in the end anything after the cat doesnt need to be touched. NA cars are different than boosted cars. If you really want to do it the right way get some rockers at least. if youre trying to stay within a budget follow what blue said IMO.