I had a chance to fly the 13x4W on my 5 pound Laser 3D. I was having throttle servo problems, so I didn't do all the tach testing that I had intended.

Wildcat 20/20
OS F
APC 13x4W
Muffler: OS 70/90 Surpass with elbow header and OS 90 degree "In Cowl" header. (Sounds cool!)

11,300 peak. Backed out to 11,000 for flight.

Very good performance! Quick spooling. The new exhaust system has less back pressure, and my midrange needs some tweaking. The throttle servo went wacko as I landed so I had to cancel testing early.

I also have some Zinger 14x4 props, but they are a bit noisier. I will run comparison tests with these, and the APC 14x4W the next time I get out.

Chuck