After buying a Cummins 528 and correcting all of the problems with it, this comes up!! I just invested a fair amount of $ with Jeff @ Modern getting the MP heads straightned out, sloppy guides, bent exhaust valves, junk springs, retainers, locks. At the time, I talked with Jeff and he said that he had not experienced the seat issue, but he had heard of it second hand. I appreciate the guys who know of this first hand reporting it. I can't help but wonder, surely there must be some way of identifying what the conditions are for this problem. If it is just poorly installed seats, bad seats, or a defective head casting, there must be a way of identifying the cause! As a potential victim of this, I don't mind kicking in some cash to have the defective head examined to determine the cause. It would be worth it to all of us with these heads to find out what we can do to keep this disaster from happening to us. I can't afford to lose the investment I have in my Hemi. Lee.