I have an OS .91 Surpass II in my Skybolt ARF which is working well but i want just that little bit extra power.

Which engine would you choose between the Saito 125 and OS 1.20AX with Bisson Pitts Muffler?

I know the Saito would be an almost drop-in fit and probably wouldn't need any cowl cutting.

But the 1.20AX is substantially cheaper here and i also figure i can save on fuel costs by running on 5% Nitro.

Would either motor with an APC 15x8 be an improvement over the .91 turning the 14x7 at 9,200?

Would the stock 1.20AX muffler with the angle adapter fit within the cowl like a Pitts?