wrong forum, but I'll chime in, anyways....

it all depends on what the resistance on the subs are. something tells me they're 4ohm subs. and they look like they're dual voice-coil, as well. dual voice-coil is one of those neat things to have that really doesn't help much, IMO.

you're probably running too low a resistance for the amp, which is over-working it and causing it to over-heat. try unplugging one of the leads to the amp (it won't sound as strong, but will run without overheating).

your subs will sound better in a sealed box pointed to the trunk vs a board with them pointed into the seats. there's more space to resonate.

if you're intent on using both voice coils, get a better amp thats stable at lower resistance.

if you don't understand resistance and ohms, go to a stereo shop and get schooled.