ya i figured that downfiring would screw with the frequency, my other system had the 4 12's sealed firing foreward and back and they hit pretty hard but sounded terrible, but now I want something that just sounds good. I decided to go with 2 10" Rockford Fosgate T1's. Hopefully I can get enough space for em and still not take too much trunk room. I think for a vented enclosure they require 1.5 cu/ft a piece. Anyone had any experience dynamating their doors? I had to remove one of the door panels from my old car and that was a pain, so i was wondering if it was worth it, cause i know everything will rattle once the subs are in.