Lynn,
I'm not sure if you recommend the Autolite AR2592 just for the 
Leading or for all four?
Buly

Both. The trailing runs hotter than the leading.

 

The worst case of a failed plug I pulled off was in the Fiat. I left a warm-up plug in it along with 3 N59Gs. After one lap the driver drove it back in with a strange popping sound and no power. The center electrode came out of the plug and was still clipped into the plug wire. The ground electrode was gone. Having escaped without doing any damage. I installed the 4th N59G and all was well. That was when we could still buy 110 avgas at the local airport. The fiat had a 14 to 1 compression ratio, and did not suffer fools lightly.

 

Lynn E. Hanover