It is true that its not the best install practice to mount an amplifier upside down, however, being such a small amp and properly tuned, it hardly gets warm to the touch with normal listening volumes, not at all on a cold day, and being mounted right above the ports for the sub box, it has plenty of air circulation and has proven not to be a problem. All amps are properly grounded and have been tested to have a very low resistance, using proper gauge wire. In addition, upgraded wire has been added under the hood. Also ran new power and ground wires for each head unit up front. Sure, the installation may be a bit messy, but this system sounds awesome, and thats what matters to me. I appreciate your input though, and Im always open to advice and suggestions.

Note MTX TC4001 has been upgraded to Exile 1200.1, and double DIN nav unit has been added up front. I cant re-edit my original post apparently.