A few questions about my best-bet configuration.

[Mr. Wild]

Just my two eurocents..

If you go active on the zx450 but decide to wire the woofers bridged then you will lose stereo separation on the woofers. Might not be a big deal with the woofers in the back. Bridging the woofers in series 8ohm will not bring ANY gain in power. Bridging them wired parallel 2ohm will bring huge gains in power but with less control.

My only concern is the crossover without any woofers connected to them. If its second order or greater, the unused lowpass circuit of the woofer is a series resonant circuit to ground. At resonance frequency it will be an almost direct short to ground. The resonance frequency might well be below the range the mid/tweet are fed so it probably no big deal.

[Pillow]

Yes, to the 0 gauge wire.

And I would add that you desperately needs some sound deadening. All that exposed sheet metal makes me think of rattles Trust me, sound deadening helps tremendously!

Also I would bi-amp off the MB Quart crossover if it were me. This gives PLENTY of power to the 3-way system and allows power adjustment for the 8" midbass if you want to add some kick. I think if you tri-amp the setup you will overpower the speakers.

FWIW in the next few weeks I will be setting up a 3 way in my suburban using the MB Quart crossovers in the front doors. Using a Xenon 200.4 to power 4 component sets. Essentially each door will have a channel off the amp... If I did not have a third row in the Suburban, I wouldn't bother with the rear doors at all.

As for your setup, once the front stage is installed, I would at least consider removing the tweeters from the rear deck. At best rock the 8" midbass in the rear deck off the ZX350, cross 60-500Hz. Unless you are going SPL, which is a different ballgame.