I can see it does strengthen up. I took the pictures below with the tube just sitting on the runners, and the runners are not even welded or anything to the flanges.
I've been experimenting and practicing on hammering a curved entrance to the port. It'll never be perfect, but I'll see what I can do. My airflow friend says a 1/2" radius is as close to ideal as a curve would get for airflow, so it gives me something to shoot for, but I know it'll come up a bit short. I started with the trailer ball hitch (2-5/16") to round out the port, then it seems the easier to use the anvil to start shaping then finish up with a piece of round 3/4" pipe. I will have four more practice pieces before I have to actually try it out on a runner.
Going for a 1/2" radius. IMO, not terrible terrible, but not winning any awards either.
Three runners made up.
And everybody likes a good mock up. The tube is a bit far forward, and up, compared to where I intend on placing it.
I was surprised my cell phone camera flash actually makes it to the end of the port.
