I use a -9 but have used an 8 also

 

so your above a 200 shot? I may need a 9 by the time its all said and done...

 

I would use atleast an 8. These cylinder heads are efficient enough that they don't need a real "hot" plug to complete the burn

Having said that, I have sprayed my truck on the dyno with the tuneup I just gave you with a -7. Everything looked good but there were a couple holes that were noticeably warmer. Could have just went to an 8 and probably been fine but went straight to the -9.

Yes, I spray over 200 lol

 

Thanks for the info man! I want to see how far a 100 shot will take me, and work my way up.