[bestatchess]

You will need to upgrade the size of your wires (ground & power) and use a bigger fuse with a bigger alternator.

IMHO, the way to find out if you need a bigger alternator is with a DC clamp meter. If the stereo is pulling more juice than the stock alternator puts out (after powering the truck itself) then you will be constantly discharging the battery (particularly at low RPMs). If you have somebody increase the engine RPM while you watch the clamp meter, you can determine your break even RPM. You will find that the stock alternator has very little reserve at idle.