Ignition setup
Haltech E6K
Leading- Crane Hi-6, 2 LX92 Coils
Stock trailing coil
MSD Custom wires

22psi boost, C16 Fuel

I run all EGV's for plugs

I was running all 11's, without issue, but on one run I seemed to foul the leadings, ( had bad ignition breakup off the line) so at the track I replaced them with 10's then clicked off 2 10.90's back to back.

flash forward 2 years, im getting ready to head to the track friday night/ sunday (weather)
figured i might aswell put in fresh plugs, and put fresh 10's in the leadings, then when i pulled the trailings i started wondering if running all 10's would be more aplicable of a heat range w/c16.
When Kahn Tuned it i was runnign all 11's for heat range, but a 50/50 c16/ultra 94 mix
so now that i run strait c16 11's seem to be 2 cold of a plug.

Now I cant really read the plugs as the starting and letting it run till NOT to make sure seals didnt stick over the last 2 years has made a true reading impossible, but for the little it has run it have some carbon buildup on the trailings.

so......

 

10's should be fine for what you have. You could probably get away with 9's also. 11's seem to much.

 

Once you hit over 30psi, then I'd go with the 11.5's....till then the hotter plug is pretty safe