Shelby GT 500 questions

Hello Everyone!

I am new to the site and am starting off my first post with questions....:D
I have a 2011 GT500 convertible with the less than stellar Shaker 500 stereo system.
Has anyone here upgraded this system in a GT500 or a GT Mustang? The Shelby forums have been a bit sketchy on this topic.. since they are more performance oriented.

What I would like to do is retain the stock head unit with the Ford Sync system, replace the door/rear side speakers with appropriately sized/ efficiency matched speakers and fab up a proper amped sub system.

My goals are to have a better sound system without a major hack job on the car.
What I have learned so far:

I could purchase a lockpick component to bypass some of the constraints of the stock headunit-I was also advised to not do this since it can cause problems with the functions of the Sync system.

Doing a sub system in the trunk of a convertible will sound like crap since there is a space where the ragtop fits between the trunk and the cabin, interfering with proper spound transfer.

I have considered doing up a custom powered, removable sub enclosure moulded to the axle hump on the back seat to get around this problem.

I don't need a full on audio system for this car...It's an in your face, loud beast and with the top down you can't hear musical nuance anyway.

I have done the full on audio deal in a '91 MR2 I have and I don't want to go to the same extent with the Shelby...Just cleaner, clearer sound with some sub bass!

Any advice from this group would be appreciated!

I would say upgrade the speakers, and leave the head unit/SYNC alone. It seems like the weak point in Ford's setups is the loudspeakers while the amps are decent. Looks like you either have one or two separate amps for the left and right subwoofers. If you go through and replace all the speakers and subs, I think you might be pleasantly surprised with the result and forgo the extra sub enclosure.