ORIGINAL: ir

My own experience....

Super tigre 51 on apc props only with wildcat 15% and Jett turbo muffler, temp 90 F, humidity way above 90%, benchran:

Apc 12.25x3.75 - Ideal running, 12800 rpm. My opinion its loud. Screams.

Apc 13x4w - Still nice and smooth, 10500 rpm. Sounds better. However I was blowing plugs. (exaggerated it was only one plug)

Apc 13x4 - It was a mistake getting this prop. It would be very similar to the 12.25 prop since its non wide. Never used, still NIP.

Maidened a Veko f3D using 12.25x3.75, more than enough powah. I was making big loops on less than 1/2 throttle, straight and level at 1/3. Currently the ST has been overhauled; new ring and rear bearings. there was almost no compression previously. If I can get the 13x4w to run above 11000 rpm, would consider using it. And yes I am going to richen my needles to stop blowing plugs. I didnt know the Jett mufflers need different kinda tuning procedures http://www.jettengineering.com/tech/techcarb.html