I have no plans to do the rest of the speakers (for now...possible future project)...for my listening purposes, I run only the front stage, and if I want, I can source from the factory head unit and have the whole 5.1 setup running (albeit with mis-matched speakers). I'd actually be more interested in going to a three-way speaker (midbass, mid, tweet) set for the front stage and moving the tweets to the a-pillars to gain a little stage height before I'd even think of providing for additional channels of output (center, rear surround). Additional speakers for two-channel sources can hinder a good sound stage as much as they help, if you don't do a lot of tuning and process the sound properly.

I sure ain't missing that center channel on my dash, nor do I feel a need for new rear-deck speakers.

I'll be working on the sound processor trim over the next few days, as well as getting my tweeters set up right. I just finished the amp rack in the trunk, all I have to do there is fab the false bottom (easy). Still agonizing over that HVAC display LCD I moved...I can make it look good, but it's prone to movement and I can't help but thinking it could be better.