Good news! We finally got around to finishing the swap and the new Stellings are installed. Here are a few pictures taken with a camera phone. I left the mufflers on rather than installing regular exhaust tips, but I am wondering if I can remove the internal flapper since we have the rubber ones on the outside. You can hear the internal ones "flap" open and closed at idle. No bid deal, but if I could get rid of that noise I would. Any ideas?

Anybody know if we can remove the internal flappers in the mufflers? We have rubber flappers on the outside.

HD,
Looks sweet, sorry I don't know the answer to your question about removing the internal flappers in your mufflers. But I would take the safe approach if it were me, and keep them. I have the same set-up w/o mufflers.
Dean

Stelling makes great headers, and Randy is great to work with.

Anybody out there have any experiance with the Stainless Marine and Stelling headers on the 525s? I am looking at Stellings, Stainless Marine or others. My first Fountain cmi/merc experianced a pin hole header leak at 18 hours. My second Fountain had the new style cmi/mercury headers one of those literally leaked with zero hours when we took it out of the box. To cmi's credit they repaired the 18 hour used header and replaced the new defective header. Now I have approx. 15 hours on the new set of headers and I did a leak down and as a result found one of the headers is leaking. Pulled the head found signs of salt on 4 of 8 valves and a seized ring on one cylinder. Fortunately I drain the headers after every use and caught this problem before it became a more serious problem. But it still looks like its going to require a valve job and pulling the motor and one piston at about $ 3,000. I really can't believe such great engines (525s)could be attached to such a crap header. I can only imagine the scope of this problem and what it has cost consumers. I have read the previous replys any further input regarding cost, reliability and service of other manufactures would be greatly appreciated.

I think I am going to design and offer a drill and tapping kit to fit the Mercury HP525 cylinder head so you guys can drill and tap the two added exhaust flange holes needed to buy and use some of the many other brands of crack free headers and header manifolds that are in the market which should eliminate this cracking/pinhole issue which appears to be damaging a moderate number of Mercury HP525's. Its nice that CMI seems to be paying for some of the actual header repairs for some users, however the engine damage, potential engine damage is not covered and obviously that is going to be the big expense and issue.
Give us some feedback here and let me know if there is enough interest in this type of refit kit in the market that we can justify making one available.

Best Regards,
Ray @ Raylar

I had to drag this thread up. I have a single engine boat in our shop right now that was factory eqipped with a 525efi. The starboard header got hot enough to melt the bellows and make a huge mess. Water in the header tube, thermostat OK, water pump OK, a little sand, not enough to cause a water flow issue. What do you think?? Header issue internally?

I think that's a great idea, it would give a lot of these guys more options to work with.

Even if you have to buy your kit, the "other" options (which last longer with 5 yr warranty) cost significantly less anyway.

Had my cmi header repaired already this season.

So it doesn't matter what year the 525's are, they all have this problem STILL?
That will make me think 2x about buying a boat with 525's!
Dean