When my engine was pulled last year, there was some rust in one of the cylinders. It was honed, new rings, etc. What I don't know is if the headers were ever checked or if it was just assummed the water was due to reversion. Now you guys have me all worried.

I replaced the CMI's with SM on a single 525efi and didn't notice any difference.

I didn`t notice any difference either.
Actually thought I picked up some power .

This what you're thinking of?

Yes I have that file, I could see if I can convert it to a jpeg.

On the 525's too SM I do not have the dyne curve but have seen it, ran back to back on the same dyno. You may not have felt it on the boat but the curve showed it as a great way to make a HP500.

Most of the loss was above 4600 rpm.

I would love to see a test like the one posted above but with a 540 that starts around 600HP or so. The best would be run it like some guys do, no water pump, no flame arrestor, no sea water pump, no alternator, no power steering pump with dyno headers.

Add all the acc run again.

Then start putting different marine headers/ manifolds on.

The other thing I always see is "its got a SC doesn't matter". Still takes power to turn those and if there are restrictions, going to take more.

How much does it matter on a heavy a$$ pleasure boat,,,,,, well until we see the dyno no way of knowing.

Lets see if this works, surprising results.

I think you just gave me glaucoma.

LOL, I could save each page, higher res. But I do have a day job!

I forgot there were 5 pages to that file. Went back and looked at the PDF.
Tried to attach the PDF.
I get an "issue processing the data" alert. Won't attach.

Any pictures of a drain plug on a header?