I suggest you have the shop check your alternator for excessive AC voltage as well. Best to connect volt meter at the alternator, AC selected, elevated rpm with an electrical load (lights etc.) Anything over .5V and it's time to hook up the oscilloscope to confirm.

I've seen several driveability issues in the last few years that were traced back to a faulty rectifier in the alternator.

As for RFI, are you running non-resistor spark plugs and/or metal core wires?

I would think a capacitor wired into the batt and ign. leads for the Sniper module would take care of any issues.