Is this a decent RPM for this motor with about 32 ounces of fuel through it?

Engine: Super Tigre G-51 Ringed
Muffler: Stock
Fuel: Ritch's Brew 10%, 11% Synthetic / 11% Castor
Propeller: MAS Beechwood 11x6
Conditions: 70 degrees, Elevation: 620ft
RPM: 10,700 slightly rich

What could I expect with a quiet tuned pipe and header with this engine? I'd like to be able to turn a 12x4 well above 12,000 with a pipe. Is that too optimistic?