I dont have a convertible but I bought a box on eBay for my 02 Mustang and have always liked Power Acoustik. I currently have 2 12'' P2 subs with a Power Acoustik 3000 watt amp and that is more that enough. Get a wire kit with 4, 2, or 0 guage power wire. 4 being good enough, 2 better and 0 guage being the best.
2006 Mustang GT E-Force Supercharger 444rwhp.