thanks for the replies..... they are the new XR's I knew they come on the 600 SCI but Merc does not seem to post torque #'s on the engines..... I just wanted to see if Merc actually had a torque rating on them... running twins just did dyno's 525SC reliable 575HP 600 Torq... I know I am safe as long as I don't pound on them hard... Heavy Old Formula boat anchor compared to the newer boats.........

I've heard a lot of guys say that, if you're running too much power through a drive, it hardly matters how you work with the sticks because they aren't going to last either way. But I've also heard a lot of people say what you're saying here about hole shots and big water. So what's to believe? Hard to tell.

After running 525's with Whipples for several years now (and an XR rebuild) in a Fastech, I will tell you to believe it all. Yes, shock in big water will kill them, as will hole shots. I used to think that if I worked the sticks carefully, I could get them to last. You can't. Rough water blew my first set, but when we opened them up you could see the pitting on all the gears from the extra torque. They were going to blow in any scenario.

Bottom line is if you make more power than they can handle, they will eventually go. Even with stock power over 500hp, I would be worried in a heavy boat.

Either you rebuild every 2-3 years or bite the bullet and upgrade..

The case looks different but structurally & mechanically they are the same inside.