I have modified my VHM heads, and am doing another two sets now for two other 300 engines I'm building.

They are of course NSR150 VHM heads but for the front head to work properly we must change the spigot position.

If the heads are ordered for the 300 kit (not for the NSR150SP), then the heads will be supplied ready to bolt on, with the insert that I've got fitted now, which is for 95ULG. Throttle response is instant and power is immense.

Other inserts that VHM have machined for me are for 100LL avgas, 108 oct. ULG race fuel and we're now designing for VP C-16. They'll make any insert I want if I ask them nicely

I'll post the weights and comparisons up tomorrow.