Sporty,
I too have built the SIG Citabria and I will tell you that it is a sweet flying aircraft. I put a Magnum .52 four stroke in mine and it had gobs of power for anything I wanted to do. That little engine runs great, sounds great, and will not kill you in the wallet when you buy it. I did a sunburst pattern and it was easy to see in the air and looked great on the ground. Take my advice however, and beef up the center section of the wing a little. My wing eventually folded while I was pulling out of a loop and the airplane was totaled. But it was one of the better flying airplanes I have ever had to that point. The wing folding was my fault as I failed to throttle back at the down-side/bottom of the loop. But, I would add a little reenforcement in the center section just the same if I were to build the airplane again. Razorback11