Looking at a couple boats with the above listed power. Is there any physical differece inside these two motors, or just tuning to get a few more HP out of the HO?

There are some physical differences internally. The MAG-HO had a forged steel crank and the MAG has a cast iron crank. Other than that, it's a different cam and programming.

I don't think there's an outside physical difference but internally there are a few. The HO has better crank shaft, cams, and pistons that have a greater wear factor and are much more capable of taking on any modifications like a supercharger. My recommendation is to get the HO motor. You'll love the extra 50 horses and the upgradability.

Here are the spec sheets for both:

496 standard

496 HO

Baja Daze, what you say is true, or I should say "used" to be true...Latest information is now the crank is the same as the one used in the HO was overkill!!!!! Now the only difference is the cam and slight tuning of the ecm to include the higher rev limiter...No longer different cranks...
Just my .02 worth....and Mercrusier's

srpbaer,

It's funny, because I had originally written what you said, remembering that the change was made for both versions to be cast...This was also reflected in the GM specs(same one's I posted above) during that time.

But now once again, if you look closely at the specs, they are different in the crank: HO has forged, standard has cast...That's why I edited my original post.

Did they go back to forged on the HO? Or does GM have a typo?

Daze, I too was told two different stories and finally asked the tech at the dealersip..His reply was it depends on when the motor was made...early ones had differetn cranks and the later ones are all the sames...Now just what does that mean?????? I think he means they changed it in mid-year but did not change the spec sheets posted on the net...Just my guess!!!!

That's probably the case. Thanks.

Yes, that's correct. It is a mistake by GM. If you look at the spec sheet on the HP3 motor, even it has a cast crank.

as of 9/9/2003, in the GM Website... The "specs" on the HO list the forged steel crank but the "description/paragraph" portion has it listed as a nodular cast crank.
Go Figure!