What would be the difference other than $600 of using a $700 Eagle 4340 crank versus a Lunati or some other $1300+ crank. We're talking for your average 800 hp 540 blown marine motor. Is it worh the money? Less flex? last any longer between rebuilds? or just better bigger black hole for boaters?

If you do a search here on Eagle engine components, you will find that most everyone , myself included say they are Chinese junk. Dont skimp out on internal engine parts, especially if you are used forced induction. My suggestion would be using Callies Pro Magnum, or at least their Dragon Slayer..

What Vinny Said.
800Hp is not average. Think of the $$$ a failed crank causes.

I've had two motors making well north of 1k with eagle cranks with no problems, with that being said I have switched to Callies just because of quality control.

+1 on the Dragon Slayer. Price difference between the Eagle and DS isn't all that much, and the quality seems to be a lot better.