RE: House 0f Balsa 1/12 P51 (.061-.10) build
I know of a $29.99 engine that can get you 130 mph.
I like the idea of the OS.18, but there's no way I'd cough up $40 for that carburetor. Just run a venturi with a remote needle valve .....and a home made fuel line pinch to shut it off.
With the .18 I'd want to see a potential greater then 150 mph before spending that much money.