Please don't "upgrade" your base audio to the shaker 500. My 2013 GT came with the shaker 500. All the speakers and door subs are all paper with tiny magnets. Don't spend the money on shaker premium door panels either. Buy a pair of JBL p660c speakers on amazon for your doors. They are 2 ohm just like the stock ones and will sound amazing. Forget the rear speakers and spend your money on an amp and sub. Now you'll have a system that will sound much better than even the shaker pro!