Well maybe the 5gens fit on the 4th gens, butn ot vise versa maybe? i know that on my 4th gen, the support bars were close to the firewall...and on the 5gens it looks like the support bar are closer to the engine block...so maybe..how do i put it...i'm visualizing it mentially becasue the bar did not fit once my h22a was in, but it does fit on the 5th gens...because it doesnt come close to the block at all..get what i'm saying sorta? ahh who knows.