RE: Sig Mustang 450
Frank,
The exhaust system makes a difference. If you're using the long tuned pipe that most DF engines come with, you may get a little more out of it. The props that HighPlains suggests will work, or you might go up to an APC 9 x 8 sport prop (wear safety glasses). If you're doing pretend Formula 1 racing with the open extractor and higher nitro, go with HighPlains' numbers (and wear earplugs). In either case, keep it on the rich side for longevity.
Duane Gall
RCPRO