Apart from not disliking the sound on my 4 door which I think is better then the 3 door. Am I missing some thing when you say your taking a feed from one of the woofers. I'd be surprised if the head unit has a crossover in itThanks for your reply!
I guess my best bet is to take the signal from a under seat woofer, and hope that I have enough frequency adjustment on the amp that I´m adding to make it sound decent.
Read somewhere that the door speakers where 2ohm? which narrows the selection of replacement speakers down...
and would rely on the speakers natural resonance so it would be a full range source, but surely you'd be tapping into either the left or right stereo feed and would not get the correct output for the sub.
Or have I got things wrong.