if i remember correctly the perrin uppipe is non flex, which tends to lead to leak issues. i assume since you're looking at uppipes you have a wrx. i'd just pick up an sti stock one. cheaper and works better. make sure if the heatsheilds are still on either pry them off, or tack weld them on.
as for turbo back, i used to have the perrin dual pipe cat back. it was an awesome exhaust with good sound. they tend to be loud. i assume their DP is catted however, which i have no experience with