Let's not turn this is into an anti-American thing. I certainly am as pro-US as the next guy, and I don't think I have ever said anything to the contrary. In fact, I've often said how I like to buy US made products over foreign made in the past. I don't know where you pulled this negative idea out of, but you should stick it back there.
Now, this is the first time I've ever heard anyone say that UPR products are made overseas. Mine didn't have any stamps on them indicating that, nor did any of the materials that I recieved with them. Their website also mentions nothing of this. The quality of them was no less than top-notch regardless of whether they were or not. I didn't buy them because they were the cheapest, which they certainly weren't, I bought them because many of the top racers in the country use their parts, and after speaking with some of them, I was sold.
I know that some (not all) of their products are "copies" or similar to other designs. So are most other companies on the market. It's not really fair to single out one brand. Some of their products are obviously engineered by them as they exist nowhere else on the market. That part you are definitely wrong on, as you can look and see plenty of that.
As for the battle boxes -- I went with UPR and I see no reason not to do it again. The steel was plenty thick, 1/8" IIRC. I doubt anyone else is using thicker steel, and if they are I can't see that it does anything for them.
BTW, If I called a company and asked them to compare their product to another companies similar product and they said that the other companies was better, my jaw would hit the floor. The fact that you say you did makes me wonder why you would even think to do that at all.
-----
Once again -- if anyone can give me a reason not to use UPR products or to look at a certain other brand, I am open and willing to listen.