just a cat back isnt going to make all that much more power. i would say not really noticeable. i mean think about it, everything up to the catback is still the same size and thats where most of the restriction is. the sound will be noticable though. i would still try the reset. usually i just pull the negative off , press on the brakes a few times and throw it back on. then go out and drive it spiritingly. does it seem like something you could be imagining? i mean were you expecting alot? sorry i cant help out too much more.