Hi all!

Looking for advice on speaker location for the front of this vehicle. I have two specific things I'm asking about: Center Channel Speaker & underseat speaker.

The vehicle has: Front door - 4" & tweeter, Front Dash center 4", Under front seats 8" sub, Rear door 4", Rear deck 4" & tweeter.

For the fronts, I'm wondering about if to use the center speaker, or just disconnect it and leave it. Where can I buy, and how do I power just a single speaker?

Then, instead of the 8" sub under the seat, I'm wondering about maybe using that spot with an adapter to mount a 6.5" speaker, part of a 3-way with the door 4" & tweeter. What are the pros and cons of the 6.5 under the seat, will I lose any effect or is it a dumb idea? There will be either a single 12 or 2 10's in the trunk.

edited to add: My goal is SQ.

Thanks!