The best plugs I have found are the Autolite Racing AR3932 and AR3932X.
I have a Stage 3 Running 21psi and have tried 071's NGK Denso Champion etc. all of which burn up or need regapping frequently. Then I found that the Autolite Racing AR3932-AR3935 (heat range - cold to hot) are identical spec to the 071's due to the fact Ford used to own Autolite. The AR3932 etc. are much better made with a solid tip (no more pulling it off with the boot), and nickel coated, so easy on our aluminum heads. The ones I like the best, having run them for 2 yrs with no issue are the AR3932X NASCAR plugs, available on eBay for about $5 a plug. They have 4 ground points and the gap never changes. Highley recommend them!

- Karma Cossie