befor you go out and spend all that $$$ try something simple look at all your battery wires then look at the neg (-) wire and think about it you have all the electrics comeing out of a few wires and all the power trying 2 jam its self back through the 1 wire to the (-) do what me and all my friends have dun get another pice of the amp wire and run another (-) from your barrery 2 the body of the car and see how much of a differance it makes

This is a simple one, run zero guage cable on your main power run, alternator upgrade to a 140amp unit, second battery around 600amps in rear problem fixed.

if your voltage is running low to the amp then it will run alot hotter and could start to distort which will screw up the amp long term and subs

check all the earth cables and possibly put some bigger ones in

awesome thanks guys, got heaps of stuff to try.. first ill check my current setup, and look at the power and earth cables, and see what I can do, then if that fails i hear cap's arent too expensive these days so might invest in one of those!!

thanks again everyone for their replies