Keep this in mind:
MSD recommends connecting the heavy black wire directly to the Negative Battery Terminal
. A poor ground is a common cause of Ignition System failure. It is NOT recommended to rely on the frame, chassis, solid engine mounts, engine plate, roll cage, body, firewall, fender or any of the like for the ground circuit.
MSD recommends connecting the Heavy Red wire directly to the Positive Battery Terminal
. The alternator produces a lot of electrical noise and can affect the charging circuit for the MSD box. It may also be producing a power spike that can damage the MSD box as well. Connecting directly to the Battery+ will allow the battery to act as a filter to absorb most of the electrical noise produced by the alternator.
I also installed an MSD Ignition Noise Filter (MSD PN 8830) in order to maintain a clean voltage signal to the Ignition Box
. This filter reduces/eliminates ignition noise in the radio and, as a side benefit, protects the Ignition from voltage spikes and current surges. It easily installs on the Positive/Negative Power Wires between the battery and the Ignition Box.
The summary is connect your MSD Multi-Spark Ignition power supply directly off of your battery, the ground being most important
. Since I learned to wire this correctly, I have not had a problem for the past 5 years.
And, Yes. My engine does in fact run much better using a Multi-Spark Ignition.