Gonna build a sealed enclosure for 2 Q 18's.
2004 Tahoe. Subs back or up? I'm thinking back but I get close to the lift gate that way. 21 inches high keeps the amps under the headrest.
I was going to start at 8 cubes per and let displacements knock it down from there. That keeps me the best distance from the lift gate.
I'll pretty much have the amp rack right on top of it.