there a few main points to remember, to help prevent "noise"
-keep power cables as far away from your RCA's as possible. (by this, run them down opposite sides of the vehicle, take the seats out if it helps).
-Ground you PC case (when you make it) and ensure all grouding points are making good contact
-ensure you use the shortest ground possible, some people also find a "common" ground useful (by which ALL negative leads will ground to the same point)
-because you are using two amps, run one larger set of cables big enough for both amps, then use a distribution block to power each amp from the larger cables, this prevents running several lengths of the same cable.
-if necessary, install a ground loop isolator (helps reduce noise in a system)
best of luck...