2001 Merc 280 EFI Sport - 27 hours in 2001 ran strong - 5 minutes into 2002 season # 6 Cyl came apart and actually broke thru block - destroyed so bad dealer guessed at root cause - under waranty Merc sent new powerhead - I broke in by the book but also kept motor trimmed in to work it hard - RPM limiter let go at 3 1/2 hours - motor blew at 4 hours - looks like detonation/and or overheating as cyclinder (# 6 again)was scuffed -Merc indicated several powerheads were built with wrong coating on cylinders and promptly sent another new powerhead at no cost - I run 92 octane with no ethanol - 40 to 1 Synthetic (Synergyn) pre mix - any comments or suggestions? Should I break it in easier and not put such a hard load on it? Size of our lake limits WOT to < 2 minutes