GAsr5, I'm doing 6.5s all around, the front doors will take 6x9s, the rear doors and hatch are 6.5s. The 900/5 if I go that far, will run the front component set on the front channel, the rear doors / hatch in parallel, and the single sub channel will run the... sub.
Subs, I'm down to one of the JL Powerwedge 10" boxes (prob the 10W3) or the Microsub 10TW1. That is unless I get adventurous and try what uplusd did with a stackfab style (I'll build it myself though). Reason for the Powerwedge or Microsub would be ease of popping it out if I needed the storage space, plus they are small so it should be minimal that I had to do that.
I have use JL stuff a lot in the past, and beat the crap out of them on my boat and they just kept going, so I'm biased.
why 6.5s all around? Coaxial or component?