Don't get me started on cracked headers. I've had 3 crack on my Ilmors. None could be repaired according to CMI. Do a google search about CMI header cracks especially on the Mercury 525. It's a major problem.
Were you one of the "lucky" ones and it cracked on the outside leaking water into the bilge? Buddy had one crack on the inside leading to hydrolock. You can also forget about CMI taking any of the financial blame.
Also, prepare to have a heart attack when you get the replacement cost. $3,000 for 1 used header (not a set). New, Gen 4 header closer to $10,000.