You have to remember too, when talking a cast crank.. These are not factory cast cranks. They are designed to have better fillets, which is where most breaks occur. Like anything else, ther are great ones, and not so great ones that come from the same factory. I do consider them to be a decent crank for the money. but, they have lmitations and I think Eagle is realistic with what they say (450hp). There are also better cast cranks which are not any better material wise, but are better finish quality wise. It's very easy to exceed that figure with these builds if the right carbs and cams are used. So for me, unless it's a low rpm cruiser, I'll use a better carnk. The MP/Scat cast will make beyond 600hp. I know of one that makes 600NA, and takes 150hp plate on top of it. They are really quite good for a cast crank.