I drove a 2002 33' with 496 HO's last summer. 3 people on board, 1/3 tank, temp in the high 70's and the speedo maxed at 75. Didn't have a GPS for verification. Great ride.

I just got my march PBM,
they test a 33 with 496 HO's
ran 75.2 on radar, 74.2 on gps,
but, they have added a 8" wide
pad to the bottom for 2003,
other notes: 30" bravo's rotating
inward, max RPM 4750, 1/2 tank of fuel,
temp 83*, humidity 69*, at sea level.

jt

Why did the pad increase speeds so much?

I would say, the extra lift it
develops, and to a lesser extent,
slightly less wetted area, now that
the original " pointed" keel is now gone.
just my .02
jt

Just for reference my 2000 33 will only do 69 on GPS with 502 MAG MPI's.

NO MO MONEY Lab your 26p props with mercury labbed props your boat will pick up about 300 rpm and 1-2 mph. The bad news is they are very thin an ding easy and will probably free spin some until your boat gets on plane. As far as speed goes 500s are good for about 4-5 mph over 496 HOs, liquids speeds are right on as far as I know.