Problem with Props revs and speed

[Fantasy 3]

Can anyone help with the Nos on my Props, i have a 3 blade ally with the Nos 48-78120-19 and a 5 blade ss 48-821154-17 i am having problems with speed and rpm and the manufacturer has said my boat should run with a 14-19?
i cannot get up to max revs or speed with either of these props, the ss does give me more speed but still does not reach manufacturers max rpm.

[marshmat]

You're going to have to give us a lot more data there. Boat make, model, LOA, beam, draft, weight, engine, drivetrain, current prop size, current speed/rpm data would all be helpful.