No HorsePower??

I Recently added a catback exhaust system new header and y-pipe and i deleted my cat and just went with a replacement resonator and quite honestly i haven't felt much of a difference. Could this be because in my resonator 1 one the holes for my oxygen sensor the plug is missing?? i'm just wondering b/c i thought i was going to feel a dramatic improvement in power and i'm not sure y i don't

If you don't have some kind of modifications done (forced induction, or cams/higher compression pistons, etc) then you're not going to feel any drastic improvements. It's a 4-cylinder engine, not a V6. But I'm sure the hole in your exhaust doesn't help any either.