RPM out of merc 125?

[just learning]

I have read that my 1995 merc 125 is designed to turn 5250 R.P.M. I was told by a local outboard repair man and a friend that they can handle 5500+. Has anyone tried this or does anyone know if this is true. I'm trying to get a little speed out of my ranger r70. Right now turning a 24 pitch laserII I'm only getting about 45 G.P.S.

[boats.net]

If you go to a smaller pitch prop it will increase rpm's but lose mph, you will gain on hole shot. If you want more speed try a larger pitch prop.