On mine, the fuel ramp starts somewhere around 27,000and by time is gets to around 35-ish, I can shut the start gas off. I have an off board gas system. If I shut the gas off too early the rpms will sag down below 30K and slowly work their way back up. The engine is remarkably consistent and once you learn its behaviour patterns. FWIW, I have had very little luck with powermax - especially in cooler weather, if you get liquid PM in your system the gas pressure goes down and it is tough to keep the fire going (this is from a number of different engines). Straight ordinary propane works wonders for me, though.......