i am using a st g90 2stroke in mine now. i mounted it on its side with a pitts style muffler. i am using a bisson pitts muffler. the standard slimline pitts muffler is pretty loud and the g90 doesn't perform as well with the standard slimline. however i see that slimline now has a baffled pitts muffler for the g90, which may be worth trying.

anyway i use an apc 14-6 prop on the g90- it does very well with this prop.