I had a leak in one of my headers and it cost me a motor. I sent them to be repaired to CMI one was fine, one had a leak. They would not repair the leaker or warantee it because it was a header that came on the Merc. 500 hp motor package and they were not of the same standards as the aftermarkets they sold . I tried the best welder I knew and because they are cast stainless, when weld cooled the crack would expand, we made many attempts and it still leaks. I bought a set of KE headers and they work great with a higher power band than the E-Tops. CMI's . I still have one header that was tested by CMI if anyone need to complete a set.

Yes Rrice I replaced 2 sets of headers on HP 500's with the CMI's after market version of the stock Mercury headers. They weighed also double of the Merc's. I wish my big tubes
were made with the same quality.

I believe if the proper procedures are followed they can be successfully welded . Don't let anybody bullchit ya .

Yes in most cases they can be welded, the step that most guys miss is "back purging" the area behind the weld with nitrogen or argon. It can be a little tricky to eliminate the hole that wants to form at the end of the weld puddle.

The other problem is once there is too much corrosion there is just nothing left to weld.