Find a shop around you that has a good builder (preferably over 35 for quality) and ask him to build you a horn loaded box. My dad does sound for bands and builds his own boxes, so he just shrunk his design down and dualed it to make a double horn loaded box for me that fits right between the trunk and the backseat. The amp is mounted to the back of the box and hardly any trunk room is lost. I had the same box with 2 10" RF Punch but it was too much for the small interior (I value my hearing) so we replaced the front face to drop in two 8". They sound better than most 12"s that i've heard and hit really hard with a good amp.
__________________ 2008 Dark Candy Red V6 Coupe, 18" SSE Wheels w/ Falken shoes,8" Shorty Antenna, SPEC Stage 1, Airraid CAI, 8.8 w/ 3.31, dual Vortech turbo exhaust, LED Projector Headlights, BBK shorty headers, SEIBON Carbon Fiber heat extractor hood, Sparco Hood Pins, Kenwood 7" touch screen nav/dvd, dos 8" rockford fosgate punch, SS window louvres, Midwest plenum cover, LED taillights, 93 race tune from bamachips, Personalized license plate "GOFASTR" (adds about 15 horses for the license plate) 220hp/232torq | 
Subwoofer box for a 2007 mustang! 
