It sounds better in reality, especially when it's hot. I didn't have a choice really, I bought them second hand but barely used from what I can tell. TBH though, I probably would have gone with which ever one was cheaper if I was buying new, from what I understand, they're completely the same

. I totally recommend doing this mod, it instantly makes a difference to your car where as a cat-back really adds nothing. I like the fact that, for the time being, I have an OEM tailpipe which is one thing that I'd like to keep, it's the perfect size. I think for the cat-back, i'll be going custom.
For anyone not sure what they're dealing with when it comes to the OEM parts, here's a picture. It's pretty obvious why they're so restrictive.
Also for anyone worried about MPG, the car returned 34.5MPG last night with mixed driving.