One more thing, what outdrive are you running?

Ok, I looked back on my notes, on the 25p prop I was spinning my rpms at 4700 and change, with my 23p prop I was spinning 5200 and a little.
Both props are mercury mirage plus 3 blades.
Outdrive is a bravo 1 with I think a 1.5 ratio.
Oh yeah this was all gps speeds.
One thing I would seriously look at on that boat, make dead sure that 496 is a true HO through and through, I'm not saying the guy selling it has done it but you can easily change the plastic engine cover from the standard 385 horse 496 to one that reads 496ho and sell it off at that.
Make double sure it's what you want.
But with that said it should be faster than 54

And one more thing, depending on what lake I'm on I'm either at 400' asl or a little over 700'
My fastest speed was recorded at 400'

Some brought it to my attention that maybe someone put a 496 HO motor cover on a 496 Mag. Anyone know how I can tell the difference between the HO and the Mag?

That should be at least a 60 mph boat.

My 272 (cuddy) with 385 hp 454 Mag runs 61-62 mph GPS with a Bravo 3.

Have access to a scan tool??

my 98 272 500 efi with a cuddy last year had a best speed of 70.9 gps that was with a 1/2 + tank of fuel and 2 guys running a labbed 25 mirage plus turning 5100 i also have 3 group 27 batteries ( 1 starting 2 stereo ) where as most only have 2 total so i have a little more weight than most

I'd have guessed it should hit low to mid 60's with the 496HO
To the op,
Don't let the low speeds scare you off if it's in good condition as you can always power up later
One of the members here has a 272 that's knocking the door on 100mph with big power.
See ya
Kelly

I have to agree with all the responses so far, my friend has a 275 with a 496 HO and it runs right with my Outlaw. 62-64 MPH all day long

I don't have access to a scan tool. If I could get my hands on one, would it tell what motor is in the boat?