I don't know if this is a problem with my boat or some other heats out there. When I go to take off about halfway through getting on plane by rpms rev 200-400 up like its slipping. Is this the stepped hull design? Just put a new prop on it 25 pitch powertech ofx I have a 496 Ho stock. Any suggestions please.

when i had my sprint with the 7.4mpi it did the same thing, i thought something was wrong with my outdrive, more then likley u have prop issues

With the high stock XD (19.25"s) on my boat, and a B1 four blade, mine slipped a lot coming onto plane. You probably have the same issue.
The simplest cure is usually more cup in your propeller blades. Beyond that, a 1" spacer has helped many of our Heats reduce slip and increase bow lift. A five blade will usually cure it too.
Regards,
Steve