I have a '94 z28 with LT1. I'm thinking of putting in a MSD 6a Digital ignition with 8.5mm MSD Ignition wires. What plugs are best with this setup that are affordable. I'm told that the manufacturer suggest using the original plugs for that engine and are $12 apiece, but will last 75,000 miles. Is their something out their thats just as good.

I would ask my auto parts store for regular AC Delco plugs of the GM recommended heat range for your engine. The $12 each plugs would have to be platinum plugs. Platinum plugs do actually last for 75K to 100K in stock engines. If your engine is not stock, you will have to change plugs much more often and regular plugs will save you a lot of money and perform just as well.