Well.. it's not "a" or "one" single secret, it's a combination of things. Some of them are already known and discussed in various threads. Some are more on the "informal", undocumented areas. If some one tells me something in confidence, and request not go out in the public, it will stay with in confidence. There area lot if things to take into concidiration to add longitivity to "any" header. I am not in the liberty to devolge everything I learned through my own headaches, but here is a few items.
Heat is a major factor. Water preassure alone will not help you to know everything that's going on with the cooling system. So the problem... Most manufactureres and Merc, have "preassure" sensing systems like "vesselview". No "flow" meter. The volume/flow meter systems are just coming into the market. You need to monitor both.
Draining and flushing. I would think everyone flushes the motors after salt water use. However, few actually drains the headers and keep them dry after use. They should be drained. There are some aftermarket system to drain the headers.
Installation; assumingly motors are rigged as per specs, but.
due to different set up. (IE; staggered systems) port motor VS starboard may get more reversion then the other.
Storage, no matter where but especially winter. You WILL get condensation. Recommendation, have a $10 fan in the bilge keep the system from condensation. Extending header and motor life.
Engine shut off after use.; many, just shut off once at the docks or ramps. Run the motors for a few minutes, "dry out" the headers, let them cool off before shutting motors off. Idle for a few minutes.
Compression testing. Test the motors frequently before major demage occurs.
Rubber hose / tip connection to tail pipe and transom tips. Keep it as short as possible and as stiff as possible. Viboration and movement of headers. A complicated thing, so just make the system "stiff".

To "share" a few. There is more. :)
All I will say further, is that there is a reason for Merc. bulletins and header re-designs.
I monitored and did a lot of things, but not everyting. Now I will monitor and do pretty much EVERYTHING.

I thought you had the Holy Grail on 525 headers. Good luck with the sale; The price is right.

LOL.. yeaaah.. price is right, but still got them. Some one grab these, I need to get the right set.

Can you recommend a mfg or aftermarket kit for the header drains? i can't locate a kit. Thanks.

I dont have any specific recommendation. Contact some dealers or some HP part distributors.

Fixx
 

Carl, the only to make them last long is,

a) Dont use yout boat

b) take them off and put them on a shelf and install a set of stellings:drink:

Ttt

TTT.
Hmmm.. People send E-mails or call they want them, then vanish..

OK who really want these?

headers
 

Im interested in headers have a customer that needs them please give me a call 203 912 7581

thanx Rich Northeast Performance

Old age must be getting to me. I think we talked, did you get what you were looking for? Mine are still in my living room and I need to get them out of here.