I will do more reading on that forum Thomas.. I am on there and have been checking it out just havent fount the info im lookin for but im sure more research will get me there. My boss owns an airline and I work at the airport on this stuff so we have access to 100 low lead airplane fuel which we run in most of his toys.. We just ran in the Baja 500 in a jeep TJ with a bored and stroke 4.0L inline 6 that is now 4.6L.. We ran the 100LL in that and it didnt ping at all with 12.5:1 compression and an iron head..
Hopefully these heads will work, my boss bought the engine as a package deal and he doesnt really know much about the parts he buys.. I tried to tell him to go with AFR's as thats what my machine shop recommends also but he doesnt want to do that. If they blow off hopefully it doesnt wreck anything else and I can get the AFR's after all..