Find a good ground, with the wiring you have should be sufficient enough though.To extend the power wire, you can either get more 4 g and crimp it together w red butt,and get some heat shrink to seal that and add a dist block that you can use the 8 g wire with a 25 or 30 amp inline fuse is all that amp needs.Save you a head ache in the future and you have the proper supply and distr. to add amps to your system.At the battery i would put a min of 80 amp fuse and after the dist block power to the sony amp no more than a 30 amp fuse.You can raise the amp with washers at the bolt downs to get some air under it also try help w the heat,but most importantly.. find out what ohms value your subs are,and what your amp can handle bridged//2ohms or 4ohms/??? You can look on Sonicelectronics and possibly find your subs to wire them sufficiently and find the wiring configurations that the amp can handle also.I wouldnt turn your gain on the amp more than 2 Oclock either anymore and it just runs hott! About all i can recommend to you at this time other than buying a small roll fan like Stinger makes that cost about 35 bucks .Hope this helps some what,and fix that muffler issue!!!!!