but if he wants to keep his onstar its his only option within reason.. paul said it best.. the remote line should plug into either the remote output on the highend converter or find the power for the headunit and use that.. as far as a cap, dont worry about it xplode over rates EVERYTHING and theres no way that amp is even near 600w rms.. so yea what paul said, just wire everything up and youll be fine.. i dont know if explode amps have a remote gain control but if they do, buy a controller and it will be nice to be able to controll your bass level.

welcome to the site, enjoy