First time using external amps so looking for advice or feedback on my plans to upgrade the speakers in my 2005 GTO.

Polk MMC6500 in the front doors (125 rms)
Polk MMC650 in rear side panels (80 rms)
Kicker Comp 8 in the rear deck (should be able to make these fit, rated at 100 rms but I think the free air rms/infinite baffle is about 55w)

Polk C400.4 (75x4 rms) and Polk C300.2 (150 rms) in the trunk.

Running 4 gauge (~ 10ft) to d-block and then 8 to the amps. Do I run 8 or 4 gauge from each amp ground to a seperate location?

The C400.4 will drive the rear sides and the subs. The C300.2 will drive the fronts.
I am thinking about getting a bass gain remote to use on the sub channel. Is this worth it?