I had the Borla catback on my '04, it sounds good, but it is pretty quiet honestly, so maybe that's a good thing since its the wife's car? I will say, unless you're gonna keep it forever (1 million mile warranty) the Borla catback is pretty expensive for what it is (it didn't even come with exhaust gaskets, freakin $900+ and no gaskets!) Also got the exhaust resonator deleted, didn't notice any difference whatsoever, sound or power-wise. The tip does look 100x better than the stock tip though, especially if its all rusty. The most interesting thing about that car? The traction control system, leave t/c on and try to do a burnout and it forces the pedal towards you, or at least locks the pedal in place to keep you from giving it more gas.
PS: I probably have a clip of a cold-start from my '04 5.7 GTO with the Borla system on it, so if you'd like I can find a way to send that to you, although there are also tons of YouTube videos on the same system.