That is also my understanding...you can run any .18 motor in the mod class in dist. 3... for the folks who run the stock motors in thier boats and are worried about getting blown away by boats with different motors or modified motors, havent really seen it yet..its the same old story...its about set up and consistency more than anything else....like i said in another post, The only thing ive done to my STOCK aquacraft engine is remove the head shim and the pull start, hang a Grim turn fin on it and run a 36x55mm prop on it...I havent even modded the bottom on it yet, and from what ive read thats where the boat gets a big increase in performance...so just bring em out and have FUN!!