Capacitor hook up?

When grounding a cap, you want to remember a few things. Keep the wires from the cap to the amp as short as you can, so you're gonna want it close to the amp. I'd recommend no more than 18 inches of wire. Find a good bolt that connects to the frame of the car like a seat bolt or something like that to ground to. With that particular amp, don't go with anything less than 4 gauge wire for power and ground. The ground wire going from the car to the cap can be a little longer if you need it be, just make sure the gauge of wire is nice and thick. Same with speaker wire, go with at least 12 gauge speaker wire for that much power. I've actually seen people use 8 gauge power wire to run a sub. No such thing as overkill in this department.....

oh yeah, yes you can ground your amp to the cap, provided the cap is properly grounded to the car. Also, keep your fuse for the power wire under the hood and relatively close to the battery. The fuse is to protect your car, NOT the amp. The amp has its own fuse to protect itself, but if the power wire ever got grounded to anything metal on the car and there is no fuse, then the power wire would heat up to the point of starting a fire in your car. So keep it within 18 inches of the battery and you will be fine. A 40 amp fuse should do the trick for that amp. Is it a class D amplifier??