The hotter days have had my setup running fairly poor and me backing off my timing way too much to fend off detonation. Today I popped in a set of NGK R5672A-8 ($1.89 a piece, I figured why not). Two steps colder than stock (one step colder than what I was running), non-resistor copper plug. I took it for a spin and so far have noticed an improvement in low rpm throttle response, and I have been able to get my timing retard down on the J&S a bit so far with no detonation. I'll try more tomorrow, the air is cooling now (would rather do this in hot air) and the traffic is too thick. I don't think I would recommend an 8 heat range for JRSCs with 6 psi, but for 9 psi it seems to be the way to go. I'll update this thread as I learn more.