If you're talking about the Shelby Kicker upgrade, I had it installed in my '12 GT with the exception of the main speakers. I used these instead
Infinity Reference 6832cf 6 x 8/5 x 7-Inch, 180-Watt High Performance Two-Way Loudspeaker (Pair).
If you want to keep things clean and keep the stock look this is the way to go IMO. The only problem I have is some albums are too bass heavy, but that is corrected by reducing the overall bass by about 2 notches. Other than that it gives you a nice kick in the rear from the subs. I don't know how well the Kickker's handle mid/high range but the Infinity's give nice separation.