Direction change
Again!
First, research on the black oxide shows, as does my experience with black oxide bolts on my other C4-under-F100 project, is that they rust easily. A local, good coating shop does it with the 200* process and recommends against it for those reasons. Other threads indicate that the home, 'cold' process is fragile, even to the touch, at times. The shop stated that it is an accelerated surface corrosion process that colors the metal.
Secondly, that other forum has more info on these bodies. So far, we know of 25 other cars. I have spoken to two other owners
Lastly, Jerry Marquis (amazing artist; runs Excess Engineering) took a few moments away from the aluminum-bodied 289 Cobra being prepped for bodywork and paint, to look at this tip thing. So, the new course is to hot-coat the exhaust pipes and the Flowmasters, then mount the tips, black plated with chrome or nickel, with a mechanical fastener (TBD). The genius is his idea to re-cut the tips to 'pick up' the rear bumper cover design angularity. While hard to describe, if you view the aft part of the car from the side, the rear profile will be echoed. That will look superb!
The Flowmasters will be blasted, then coated in black or dark gray, as will the 3" pipes feeding them.
Given that: 1) I was not crazy, initially, about the Shinoda-designed tips, and 2) the other cars have widely varying tips, I think this is best. The black-plating will subdue a detail that the eye will respond positively to. Closer inspection will only add to the visual delight.
I admit being excited about seeing this result! Okay, age does that to us.
TBD = To Be Determined