Well my first question I guess is? Is it a freshwater application or a Saltwater application? I don't think anyone makes a bad header today. Lightning builds the best if not only freshwater header on the market today with a warranty that exceeds CMI. Elite is correct that the after market CMI is a different version than the OEM unit. And ask anyone with a 525 Merc If they have gotten three years out of their headers before they fell apart? But I will say anyone in the engine business of making horsepower knows that the standard elbow top chokes any motor over 600HP. Did you notice Mercury didn't use them on anything over 500HP? Notice the 525 and all engines on up all have long tube headers?. I know this always starts some war because somewhere someone used them on some engine bigger than that with success. If success means that the engine made some power or maximum power well thats the determination of what success is. But that doesn't mean it was the best choice just because it bolted on the engine. If your going to build a 900HP plus engine it deserves to use a true long tube header. Take a look at these headers form both Lightning (freshwater) and Hardin Marine (salt water). Now before everyone starts screaming remember this is a 900HP plus application!!!!!!!!

My 945 hp blown 540 reverted water BAD with the lightning headers at idle,I switched to stainless marine 3's with 5" tails. They are big & ugly but work very well,Smitty

Just a reminder for anyone running a procharger,the keith Eickerts do not clear the blower at all,Smitty

It is nearly impossible remember I said "nearly" to run any wet style tail pipe exhaust system at 900plus horsepower. Lightning makes a system with a water jacketed "Dry" tail pipe that will accommodate this application with no problems.

Lightning pipe looks like it actually has runners that are close to being equal length. I may be wrong, but as the pipes become more "equal in length" or closer to being a tuned runner length, don't they exagerate the reversion deal as they in effect, suck and blow harder? Cylinder "scavenging" is improved with a "tuned header" as well? In other words, a trade off for better performance upstairs?

And the Dana's are a VERY tight fit if you go with big heads.

My motor made 945 hp and does not have problems with CMI's.

Heck, I think that Kennyo's motor was reverting pretty bad at 800hp or so with standard Lightnings.

Stellings......
over 300 hrs in fresh and salt water....
Pfaff 1000's

I think all of the BIG tube ( CMI ,Stellings, IMCO, Stainless Marine ) or what ever work great and dont have issius if installed and COOLED ( again COOLED ) right.

The biggest problem they all have to fail is enuff cooling.
They will all suck water back if the valves are overlaping to make power. But they only damage if not installed right.

My engine always has a little salt in #7 and #8 cylinder.
But never did anything to the engine because its min.
As soon as you run high RPM it will not even get there its from iddle at the dock .

You get the best power out of stellings or Stainless high tourqe III, thats a fact.
But with the Stellings ,alot of cooling is ness. and the aluminum Stainless safe weight and have no cooling issius at all. make the same amount of power.

Just what i learnd for alot of $$$$$$$$ on my $hit.

Never seen a Stainless High Tourge III ,that is not DRY ?!