Tried getting responses in the speaker sectioin, but maybe this is more appropriate given the many variables:

I have a 2007 G35 with the stock stereo. The doors have 6.5" speakers down low, but are designed to accomodate the 10" speakers that come with the premium sound system, and the tweeters are located near the door handles in an opening that would easily fit at least a 3.5" speaker.

Caveat: I don't have available trunk space for a sub enclosure, so I'm hard up to get some low end in the new system.

In the perfect world, I'd run a three way system up front, with at least 8's in the doors, 3-4" speakers by the door handles and tweeters in the "a" pillars. I don't think I'm proficient enough at car audio to attempt to run an active system, and the Dynaudio 8" 3-way system would break the bank, so I'm looking for suggestions.

There is an opening in the rear deck where the premium system would have a subwoofer, so I could arguably put some bass back there, but I've read that IB is a pain in the arse, so I'm at a loss for how to configure my set up. Could I use a 4 channel amp and use a 4" 2-way comp system on one set of channels and use a different set of channels to drive a larger speaker in the door, or is that harder than it sounds? Any help would be appreciated.