trunk setup
I have a 2000 Regal. You can fit two ported 15's depending on the space between the woofers and box thickness, I measured 9 cuft of USABLE space without the seats folded, I think the max width was 33-34", if you don't mind having the seats folded down permanently, that'd be your best bet. Those trunks are spacious. If you want an SQL system that can hit a good number then I agree with danyman, 2 12's that can handle 1500W each tuned to 32-38hz is probably the route with the least headaches.
i have used tf1 12's and they are an awsome sub, also, if your loooking for numbers you might wanna tune higher than suggested here. tuning low will be loud as hell for daily but it wont put up numbers on a meter


