the stock heads that didn't have a decomp, to my knowledge, were used on the start3/start5 motors. that's the only time i've ever seen them --- but maybe they were used on others? interested in finding out!
this is a cool thread. I just slapped a 47mm airsal kit on my variant yesterday. I cut the boost ports into the piston, cleaned up the casting a little, gapped the rings and spaced the kit appropriately and have amazing power. great for riding around the city. flew down claiborne last night passing cars. weeeeeeeeeeeeeee!