Those look identical to the Summit house brand headers.
The steel is thinner than some at 16 ga, and the welds are rough, but they work.
I also noticed the flanges that the H-pipe mounts to is thinner, and bows easily when you tighten the pipes together.
It hasn't been an issue on the Stang, but my F150 has had an exhaust leak there since day 1, and I can't get rid of it.
The paint on any painted header is also going to suck.
Strip it, clean it and prep it really good with acetone, then never touch the surfaces again with bare hands, before or after paint.
Any oils, even WD40 sprayed by someone half a block away, will settle on or under the paint, and burn it off right away.
The paint must be heat cycled once before the paint will take, and that is only if you use the proper paint.
If you don't paint them meticulously, they will develop surface rust in short order.