Hi Harold, I ran into a similar situation a few months ago on my 2008 Puma / 250 HPDI. My boat came from BassCat with a Yamaha 27m series prop. Overall performance was OK but I thought it could be better. Top speed with a full load, full of gas and full livewells was high 60s to low 70s. I spoke with Ivan at BassCat and was told that this peformance was normal and all that was to be expected with the Yamaha. While I was at a local dealership with the boat, the dealer noticed the prop and commented that it was incorrect for anything over a 225 horse power motor and that the prop could throw a blade. When I left the dealer, I went to a prop shop and was told the exact same thing. Both of them recommended a T series prop for the 250 motor. The prop shop let me use a 27T-1 VMax Series prop for comparison and what a difference!! The boat ran much better in all areas from the hole shot to top end. Back to back runs showed a top speed increase of 5 mph with the T-1. Needless to say, I now have the T-1 on the boat and the M series is a backup prop.