John,

Before relocating east of the Mississippi I lived in Colorado Springs and our flight line was up around 6,000 feet ASL so I know what you're up against. I have a Platt Spitfire that I have not put together yet but Dave advised me to use the Moki 1.80 in it for best scale performance..................at sea level. Now, I've received mixed opinions on the engine choices for the Spitfire. Some say the 1.80 does fine while others advise the additional power that the 2.10 would provide.

Sure, the Spitfire and Mustang are not quite the same but if it were me, I'd go for the larger 2.10 and be sure that I had the power on tap if it was needed. The engine is not that much larger in physical size but the power increase is noticable, to be sure. At your altitude you'd be wise to go "big". But, hey. That's just me.

Al