i just finished running the 61SF and the 61 Evo....i get about 500 more rpm tuned to fly with the OS SF61 with the same prop(12x8 mas), glow plug(os f), and fuel(15%)...the only thing is i will be using the evolution muffler. I ran the FX style exhaust on the evolution engineand i lost about 200 rpm...at this point i want all the top end i can get

if i get tired of it i can always change engines..thats the good thing....