The Resonated 3" with Catless UEL headers, perrin overpipe and 3" catted front pipe is ok until you get the engine under any load. Going up hills or going WOT results in an exhaust volume that is definitely not condusive to holding a conversation in the car and full of rasp. Pretty annoying when on the highway with cruise control on and you start going up a slight hill while on the phone.
If you plan on just getting a catback you'll probably be fine. If you plan ANY other exhaust mods, get the 2.5".