Hi Shane

I'm glad it's sorted.
The engine technology does mean that power on the RCV91CDs does vary from engine to engine. Although additional running should increase the rpm further, a 14lb model is really too heavy for 'normal' RCV91CD engines.
Perhaps you should consider getting an RCV130CD when they come out at the end of the year...that would be perfect for your Spitfire.

Happy Flying
Laurenne