Ok, for an 8 Ohm sub, it is advisable to get another 8 Ohm sub. wire them in parallel down to a 4 Ohm load. You would wire both + wires together, and both - wires together to yield a 4 Ohm load at the amp. Majority of the amplifiers on the market are designed to give more power at a lower impedence, or Ohm load. You just have to make sure that your amp will take a 4 Ohm load. Without knowing the model of the MTX amp, I can't give more advise. However, this should be able to give you and idea of where to start. The main problem is that you have a single 8 Ohm sub in the Kicker Comp.