Is there a way to check the headers used on the 525s? I have read that they are notorious for cracking. Whats their life expectancy ? CMIs made exclusively for Merc Correct? Going to be looking at a couple 525 boats.

Short answer, you can send them back to CMI to be checked.

Do a search on CMI 525 headers. Lots of info, this topic has been covered extensively.

Yeah, it's all here. Do a search on cmi 525 headers and pressure testing headers. No sense rehashing it all.

CP Performance has a very nice set of replacment headers for the 525, not cheap but a cylinder full of water is not cheap either

Is there a visual way to see if the heads have been redrilled for replacement headers?

The heads probably wont be drilled for replacement headers unless the previous owner changed the headers to a different type already.
If you need new sets, check with CMI, they have the new GenX headers set up for direct replacement for the 525 problem headers.

Best Regards,
Ray @ Raylar

Im boat shopping and Im interested in the 525 package. I had no Idea there was such a problem with these headers. I was looking towards the 525 over the 496 for possible whipple upgrades in the future and what I thought was a near bullet proof package with an XR 525 combo in stock form. Now Im worried about serious engine damage on top of 10k to replace a couple sets of headers.

Is this problem really that wide spread or is it just that there are a lot of 525s out there and there are bound to be some exhaust problems?

Good question.. wonder what failure % of the headers is roughly. 1%, 5%, 10%, 30% etc.

If my memory is correct Stainless marine also now has a set of manifolds for the Merc 525 & 700... At least I believe I saw it on the new 2011 price sheet they sent us..

Jamie / Lakeside