The p tips are great props, I will continue using them on planes regardless of the cost. They provide great pull. No rpm numbers for you though, sorry. The consensous throughout every one I have seen is the 31x11 on the DA or 3W. These are great 3D props and ok IMAC props. I say ok imac props because they are not as quiet as a 3 blade on cans. However, the princes I have seen on cans seemed pretty quiet and not a lot of noise, no more than say a mejzlik. At the hot springs fly in a couple weekends ago, there were about 60-70 planes on the field, and over half of them were running P-Tips.