I have 2 GMS's a 40 and 47. the idle mix is very touchy to set, differences in 1/16 of a turn can make a big difference. Set the high end 1st with a tach, then adjust the idle speed to @ 2300 rpm, check the transition and adjust low end mix slowly. with every tweak of the low end mix, go back and readjust the high speed mix. using a tach helps alot. I set the high speed mix to peak - 500 rpm. I use CP 10% and on the 40 engine with a 11x6 prop I get 11500 pk.

once tuned they run very well with lots of power, haven't had a dead stick once on either engine. With the change of weather here in New england I had to adjust the high speed mix but other than that haven't touched the settings.

Steve