prop size for 312 1983

[d123456]

I just bought a 1983 312 stinger powered by 1998 502 mpi 415hp motors.Has trs drives.
It has 23 pitch mirage props on it now and im turning 4800rpms.I can only get 61mph out of her I cant believe that's all she will go.one guy recommended 27 pitch clevers.
Any ideas would be great thanks.

[stinger390x]

Forget clevers as they need to run shallow and the TRS drives run too deep.
You should be happy with 61mph as that is a respectable speed for that particular hull.
Your RPMs however seem a bit low with what you have presently so putty a larger prop on will only exacerbate the rpm problem and make it worst. The engines could run about 5100-5300rpm without problems but you only getting less than 5000 means that your pushing props too big for the boat right now.