I just installed the Sniper 4150 and Hyperspark Ignition in my 69 Barracuda with 440. All went well except for the dreaded 12volt switched source that is required. I have 6 fuses in the fuse box and none that have 12 volts while on and cranking, and off when the key is off. If I use my third arm and hold the pink wire on a 12volt source and turn the key, the engine fires right up. When I turn the key off, the fuel pump keeps running. So...i know it starts and runs. There was a thousand ideas and recommendations out there on the old interweb on what to do for a 12 volt switched source in a Mopar, so i just called Holley and they said get a 4 pin, 30 amp Relay and a diode. Pink wire to 87, Ground wire to 85, Battery(+) with fuse to 30, Starter solenoid to 86. He stated that a diode should go in between the solenoid and relay to prevent back interference. I'm going to do exactly that tonight and see what happens. I'll be sure to provide an update on how it all works out.