I have a 2007 Dodge Charger that i am trying to put in 4 kicker cvr12's. I have approx. 8.8 cu ft to work with without doing a 5 sided box and using the spare tire well. What is killing me is that this car is a death dealer to subbass. I am running an Exile 1200 monoblock amp on the 4 of them at a 2 ohm load and it sounds like crap. I had the same thing in my pickup and it would knock your lungs loose. Every stereo shop that i have talked to about it says they have had trouble with the Chargers too. I have tried 4 different boxes. Upfire didn't work at all. Just shook the deck lid off the hinges. Tried to backfire with 2 12's and output was better but sofar i am using 2 firing forward into the rear seat. It sounds ok i guess but i have four and want four installed. Anyone with any clue as to what to do would be great. I am just getting tired of trial and error with this one.