Hi Jeff , welcome to the IO-240 minority. here is a copy of a response I recently sent to a new IO-240 powered owner: There are a few of us out here that love this aircraft/engine combo. I finished my Series 5 Outback back in 2003 and can't believe that I have been flying it for 13 years already. The IO-240 has been bulletproof in the 750 hours I have flown it so far. As far as my prop history goes , I started with a warp drive (Skystar recommended prop) never got installed as it was found not to hold up to the IO-240 power pulses and developed cracks. That prop was sent back and I bought a Sensenich W74EK-2-58. this is a 72 inch dia. prop (thats what the -2 means-2" cut off from the 74 " prop at the factory) This prop only only developed about 2200-2250 static rpm at full power on takeoff. I called Sensenich and they recommended trimming the prop , so I got up some nerve and took a saw to the blade and trimmed 3/4" from each end-it got static rpm to 2300-2350 and helped takeoff perf and is my most of the time prop. I was very careful and used a fine furniture builders hand saw to make the cut , then sanded the tips to the same profile they were before and added some epoxy varnish to the cut areas. i did not rebalance in any way with no noticeable vibration change. Jeff hays , another I0-240 guy on the list had the same prop and did the same thing to his. My takeoff distance solo from grass is around 350' and I cruise at 115 to 120 mph at 2400-2500 rpm variable with alt and temp. I live in snow country in western NY so I fly on skiis in the winter and needed a good up and out prop for winter ops so I bought another Sensenich prop which is my climb prop. it is designated W74EK-54 and is a true 74 inch dia. With this prop , my static RPM is 2400-2450 RPM and is a good climb prop. Cruise speed will suffer by 5-10mph with this prop which isn't a problem since I stay close to home in the winter anyway. As far as recommended torque values go, Sensenich says for AN6 bolts (3/8'') 200 +/- 25 inch-lbs and thats what I use. Like you I have always wondered about other props like a Catto or whirlwind, but at what they cost, I need to know exact specs from someone operating an IO-240 with those props to see if there would be a significant perf increase. There is a guy Phil on the list who recently completed a Series 5 with an IO-240 who is using a Catto prop but I haven't gotten enough specific data from him to make the buy. I would lean toward the Catto as guys seem to love them. It would mean no more seasonal retorques and flying in rain wouldn't erode the prop -which are 2 of my wood prop complaints. Can you tell me the history of your vixen, I thought I knew of all the IO-240 guys out there but didn't recognize your handle when I saw your post on the list. Any help you need don't hesitate to holler. I still really enjoy my airplane after all these years and know I built the right one for me. see ya later Bruce N199CL