If you put subs in make sure you use dynamat inside all of the interior panels. Everything will loosen up and rattle over time which is very annoying to hear.
On my old 02 GT I had three 10" JL Audio W6's. Had the place who installed did the install throw in the dynamat, never had a problem.
2010 GT, Track Package, staggered 20" Bullet Wheels, SLP Axelbacks, Magnaflow X-pipe w/high flow cats, SCT/Bama 93 octane race tune, K&N drop in filter, 30% window tint, Shelby GT500 rear spoiler, DG Customs quarter window louvers, DG Customs side scoops, CDC classic chin spoiler, 3D Carbon Eleanor grill, MMD painted tail light bezels.