I finally replaced my original AM radio with a RetroSound Laguna C AM/FM and some 6.5" Pioneer speakers in Rhino Fabrication kick panels. YUGE improvement, but I'd like more bass thump. No 1000W door-rattling monster, just some deeper thump. I'm wondering if there's some smallish subs that might fit behind the seats, considering I have a full-size spare on one side. I'd like to see some of your solutions.