Does anybody know if the rear sub from a GS$ could be swapped out for a better sub and somehow add an amp to it so that it would pound ? I have a JL12W7 but the bow will not fit in the back part of the trunk. Anybody here have a system in their GS4 and have any pics ? Thanks

 

Yes it is possible, several folks have put a 12 in using a baffle. Do a search for subwoofer, and you should find the info you need.