question about a 60 hp mercury

[phillyfisherman]

i have 1995 60 hp mercury its on a 17 ft tracker .my wot is like 5200 or 5300 rpms and i understand thats the right right rpm but my main question is what top speed should be. i get up to about 23 mph. i have a 11 pitch i belive on it also. it does get on plane but i think thats b/c i added one of those plane fins that go on the motor if i take that off it wont get on plane. any ideas what could be wrong or is this all seem just fine and is it worth putting money into it? some people seem to think it should be in the 35-40 mph range?