Go to welding shop and get small welding cable and run from disconnect switch to starter. The multi-fine strand wire has the least reistance and delivers the most power to the starter. Connect it to the batteries positive terminals at the disconnect switch in the rear. Ground each battery with short cables to back of car. Take another ground wire,attatch it to each of the battery grounds in back, and attatch it to the motor. Put the ground for the msd to this ground at the motor. This system gives the starter the power it needs and the msd the best ground.