I have a CMC and the header piece is made from what appears to be a fiberglass layup. A really poor quality layup, but it's fiberglass nonetheless and almost every one of them has to be customized a bit to fit the windshield top trim and shape.
I got a third CMC-style latch from somewhere and attached it to the header in exactly the same way that the other two on the ends attach. These latches are adjustable for the amount that they pull in when you latch them - pretty handy in compressing the header trough weatherseal just enough to seal properly - something I'm not sure that little clip-and-knob thingie can do, as I've never seen one in action and don't know if it has the ability to pull the header down. Still, a slick solution.
You may have to peel back the top material a bit for access to install the center latch, but it glues right back on with contact glue. I removed the windshield top trim and bent another lip in it exactly like the other two but using this latch you may not have to do this.
The middle latch is NOT installed in the center, but is 2" over to the right to get out of the way of the windshield center strut and to clear the mirror when latching it. Once this was added, I got zero water intrusion along the header at any point and at any speed (at least up to 80).
It would probably be cool to get the same latch style that you already have to match aesthetically. My entire installation process took a couple of hours and a small can of DAP contact cement (red or green) at a cost of about $20 bucks.
