Scott,
Ok, here is the deal, I am going to interview my sound technician in Circuit City on the install difficulties tomorrow, so I will have everything put together no later than this weekend. I would say the best bet is tomorrow night I will have everything ready. (Sorry Drew, just thought since a lot of people here ask me about the 850 specifically, I thought I could provide a tech. help article.) Now, back to your sub question. If you want more bass out of the rear deck speakers, I would say get the "bass-est" 6x9s you could find on the market. Don't have any recommendation, sorry. Personally, I prefer subwoofer better, because with my upcoming 2 10s Alpine Type-Rs, dual coil by the way, (currently running 2 MTX 10s, great woofers by the way.) with the help of a Alpine MVR-T707 750 watts amp, the whole car is pumping out an amazing 1400 watts altogether from 10 speakers. With your 8s, I would say if you could have a box custom made for you, like a angle mount or something, that should help you to retain some trunk space back. Good luck.