Not sure, the main thing the pic shows is that the outer tubes stop before the flange.

Also, according to the previous owner, there was a recall on the head gaskets. He had them replaced in Dec. 2005.

I was told the headers were only a problem on salt water boats?

CMI Exhaust Headers (Warning )
 

I also recently purchased an 05 353 with 525's and 80 hours and I am not thrilled with the prospect of replacing headers. One thing I have not seen addressed in this thread is that the bypass hose running from the distribution header to the back of the riser was eliminated in the later 525's. I called Mercury and CMI and both recommended sending all the cooling water through the header and getting rid of the bypass. Maybe the fix is that easy?

Ilmor IS a higher quality company as compared to Mercury and "probably" would not try to skimp on the quality of the headers built by CMI for their products. Just my opinion. I have had external leak problems at the collectors with my CMI headers on my forward motor, but Ilmor and CMI have worked with me on repairs. Ilmor even sent me a loaner set of headers to use while CMI did the repairs. Now, sport, lol, that is great service by Ilmor. Would Mercury ever do that? My forward motor tailpipes were not braced by Donzi when the boat was built, and I am going to brace them myself before this next season, which i hope will solve my leak problem. I have not had a single problem with my rear, shorter tailpipe headers.

"What is the best way to check them?" Remove and return to CMI.

:coolcowboy:

I have a 39 O.L. w/600's that utilize the same CMI headers as the 525's. This past July i needed to replace the headers on the rear motor, i hated the exisitng CMI headers, dealing with the pressure testing and welding repairs. But, my mechanic convinced me to try the Gen X by CMI and i beleived the hype.
Paid over $5k for them. In August and only 10 hours of use, i noticed some water in my oil. Only two ways, my intercooler fittings or the F-ing new headers. We pulled the headers and found cracks in the welds on both sides. My mechanic pressured tested them, shocking, they leaked. He called CMI and took pictures and sent them to CMI. CMI could not beleive their new Gen X headers were faulty, they were apologetic to me and sent a new set of headers out immedialtely, but wanted my credit card for shipping fee to send my old headers back and send out my second set, via fedex. Upon receipt of the cracked headers, they would reimburse my card of the the $400 shipping fee, seemed reasonable to insure i sent back the faulty set.. CMI never reimbursed me, they claim the headers were fine.....They do not want any negative press on the Gen X and deny any culpability. What a **** company. I would not exist if i treated my clients in this manner. I will never buy another product from CMI.

Lost Summer
 

I actually just went through the problem with the CMI headers on my 2004 525's. Second time out for the season I went to get on plane and lost the port engine. The first trip out the week prior to that the boat ran great and the wife even commented that if we didnt have another ride all season it was worth it. Well...she didn't get another ride and took the entire summer to get her back together.

I broke a valve in the port motor and it made a mess of the piston and cylinder when it happened. Pulled both engines and found corrosion on all four heads and 3/4 of the exhaust valves. The apparent cause was that the headers were leaking and splashing the hot exhaust valves.

When I called CMI about getting them tested they said that they really dont even look at them if they are older than 5 years. I have done a lot of research on this and found that my best bet would be to replace them completely and not risk fixing them only to have them leak again and do further damage. I considered several options such as re-drilling the heads to fit standard headers, trying the new Stainless Marine Headers for the 525 and the gen-x sets from CMI. All of these were valid options but I ultimately decided to stick with what came on the boat and replaced them with the OEM CMI's.

We got everything back together by the end of the summer and was able to get a couple runs before putting her up for the winter. I added water pressure gauges to monitor was pressure and will continue to be diligent with flushing after every use.

I have a buddy that has the same engines, same year, 100 hours more and used them in Salt and Fresh water in a 38 Fountain Lightning. After the ordeal that I went through this past summer he had his engines pulled and headers and heads checked for damage. He only had one header that was leaking slightly and absolutely no corrosion or water damage. He is having the one header fixed and everything back together in a fraction of the time and cost. He has a staggered set up in his and I am running silent choice in a side by side set up in a 35 Sonic. Not sure why there is such a difference in the outcome of both of these.

Hopefully some of this info will help point you in the right direction.

That is a hard pill to swallow!!
Hard not to stand up and scream "foul"!!!

Holy Sh*t!!!

He even took pictures and they still denied it!!!! This thread is giving me second thoughts totally on what engines I want in my next ride. I'd be stretching it too just to get something with 525s and new headers right after purchase would put me in a bad position!

Man, that is awful. I can not blame you for staying away from them. That's not how you handle it.