I currently have the ARK GRiP V2 catback setup (everything else stock) and I must say that it is the nicest system I have heard yet. Pretty quiet when cruising but really opens up when you step on it, this is a result of their Helmholtz technology. Lucky for you, someone is selling it in Northern California at the moment :
Ark Grip V2
FYI this retails for $1500+
Here's a clip of a fellow forum member with it on (all else stock):
https://www.youtube.com/watch?v=cudYB8E2CE0
I say jump on it, you will
not be disappointed.