If concerned about feedback from the ballast, add a diode to the IGN2 circuit but a diode connecting the IGN2 to the IGN1 would provide a constant 12V source without the need for a relay.
As mentioned, a diode should do the trick without the need of a relay. I don't run the stock style ignition (with ballast resistor), so I just connect both wires together, and use an aftermarket CD ignition box.
