No water should get to the rope seal joint unless its reverting or something is leaking. The water does not/should not mix with the exhaust until the very ends of the tail pipe. If the header pressure tested good, then my guess is the tail is leaking very close to the joint.

Pressure test done with air and with leak down tester.
Header keeps 20psi in without any leaking.

I have ask from CMI that If manifold and tailpipe seal leaks could that cause the water dropping out (pulling water backwards) ?

Here is answer:
Yes, because it is sucking in air at that point.

Regards,

David Rank
Sales Engineer
Custom Marine

WTF kind of answer is that .

Will check the tailpipe too.
but if tailpipe are ok then its pulling water backwards
to the leaking clamp.

Makes sense, the small leak would cause a higher vacuum that the standard exhaust exit, due to the increased velocity.

Most likely goes away at higher rpm.

Now I'm worried, I gotta check mine :/

The tail pipe will have to come off and be visually inspected and pressure tested. There is no way to plug the water exits inside the tail pipe without removing it.

I've seen the rope seal cause water leaks. Most of the time you'll get some water on the rear valve cover and if it's salt water you'll get a lot of salt on the rope and valve cover. This kind of leak ruined my polished valve covers years ago. Ruined the covers so bad even paint bubbled off after prepping and painting them. Good times!

I had the same problem w/ brand new sport tubes, the rope seals can somehow collect condensation simply from temp. difference mostly at idle.

Just throwing in a little advice here, the leak down tester is not an effective way to pressure test. The kind of leaks you see in a header usually don't flow enough air to move the gauge,

Best way is to pressurize with air (using the leak tester to regulate pressure is fine) then submerge in water,

Spraying the typical problem areas with soap bubble solution is not bad either.

And I do think water there from reversion is really common.