Good luck and keep us posted.I'm dealing with the same thing, I have 4 props to try and should have some more answers this weekend.I have a 26x17.5 thats hitting the limiter and i just put a 28x18 on but doubt if i can turn it with any justice, but i'm taking the 27x18 just in case. Curt

I agree with kevin that it sounds like the power is down. I was able to help test a 2007 290 with the Ilmor 620 at the factory and we were around 84 on dead calm, fresh water with a 5 blade maximus. This was the 290 featured in the ads last year.

Love that boat. Do you think that boat with a merc 600 and A/C might post 84mph also?

525s in a 290 sc hit 80-82 I would think when i get boat with the right prop set up it should do 84 - 86 mph with 600 sc in 2 ft chop 2 people 1/2 tank gas will let you know havnt had time the last 10 days to get back to testing it

Wellcrafted, I had a merc racing 600sci for 3 years in my Y2K, that motor should see 5300 rpms, at times I saw 5400. Before the rev limter kicked in.

You having any luck getting a top speed yet?