Might want to run 2 good quality 8's. I am running 1 10" JLA sub in an acoustically sealed box w/ JLA 500 W amp - plenty of bass (more than I need actually), but I find that the full range is lacking at the mid bass level. Xover set at 80 HZ so it might just be the Infinity speakers (replaced the stock junk) that might not be responding. Have you tried any dynamat in the doors and over the wheel wells? I might give this a whirl cuz it might improve the overall tone/sound.
07 Jeep Commander 4.7L FFV 4X4, 4" Superlift, BFG 285/70/17 KM2's, 4xGuard Front / Belly / Side /Diff Guards, CAI / Catback, Jet Stage 1 Chip
03 BMW Z4 2.5i ESS Stage 1 Supercharged, Staggared Wheels, Koni/Dinan Suspension, Stebro Exhaust