^^ ditto.  unless where you live is gonna be harsh on testing and checking for a cat then just get the VRS.  it comes with a cat already and bolts right up to the stock midpipe.  there's no O2 sensor behind our main cat so there's no worry on throwing a check engine light.  I've done this on my car and it's an awesome piece of work with very nicely done welds and pretty inexpensive as a catback especially when compared to some of the prices for an axelback.

i lost some torque.

but top end was a little better.

depends on how you want your power and how much.

I put a Apexi WSII universal muffler on with stock piping and a Injen Cold Air Intake and that woke my car up ALOT! I wouldn't open the exhuast up to much more becase it's pretty free flowing as it is and you will lose torque like others have said. I am like you I love torque!