60-63 at best. The Only mod to make to a 951 is a new prop. Solas Concord 15/20
it spins up faster than stock, but also let's go faster in chop, so in rougher water you may hookup better stock.
You'll gain some acceleration, and maybe 1-2 top end.
Else, stock is the only way to run a 951, and you'll get 10 years out of it or about 250 hours.