Ethanol will eat, de laminate stainless over a period of time

When I had CMI's, I always drained them. It was very easy to do, just two thumbscrews. After hearing all the bad press about 525's and CMI's, I figured it couldn't hurt.

Dave M, totally agree. spent $12K for 2 sets of CMI headers, in 8 months I had a pinhole in one of the tubes. I am extremely anal about flushing after every use. CMI said it was from salt. I boat in the north part of the Chesapeake, it's way more fresh than salt in my area.
Bottom line.....CMI headers are garbage and, they don't stand behind their junk, cost me $400 in shipping to get it repaired 8 months after purchase

A few years ago I pulled the drain plugs on mine and made 1/8 inch weeper tubes so they empty when off .

Do you have picture of that?

I do not have a pic , I have underwater exh routed from R&L header to a tee then put a nipple to the cast elbow which exits the transom .