Wow, now that's a detailed and insightful reply. I do appreciate it. Philosophically I agree with the "made in China" sentiment, but realistically half the crap everyone purchases daily comes from China. And so it goes, modern life in the 21st century. Anyway, are you going to tell me you never shop at Harbor Freight?
Re: high school kid doing stupid stuff... and burning A LOT of extra gas in the process. I've got those stories in droves. Like the time I put a 4.88 rear gear and an 850 double pumper on my 1970 1/2 Trans Am (my high school ride in Farmington Hills, in the burbs of Detroit, cir. 1979). Of course, it had the cam and manifolding to match that combo, but yeah, it used some gas. Went stop light to stop light down around Gratiot and Woodward reasonably quickly however, until I stripped all the teeth off 3rd gear. In those days seeing a Chevelle with SS 454 on the fender was so frequent it wasn't worth noticing. Whining GMC 6-71s, got most of the attention.
My username "Sportscarclinic" comes from the shop I used to own and run in Charleston, WV, before moving to Portland. At the time, it was the largest, independent import only shop in the state. Most of my 'expertise', if I can claim to have any nowadays, is in imports, specifically Subaru, and formerly Porsche. I've got a fair bit of content on Quora, mostly answering questions about engine operation, etc. Here's an example:
https://www.quora.com/Is-it-true-that-e ... a-mechanic
To speak to an earlier suggestion that I need help figuring out an engine knock, and/or finding ports on a carburetor, yes, I did. One thing I've figured out over the years is that people with hands-on experience with a specific make, can frequently save you hours of 'learning' and frustration. Could I have figured it out on my own, sure, eventually. I already had the same suspicions as to the cause. But one of the other things I've learned, is not to diagnose the problem for your mechanic, when you're the client. I provided as much, or as little, evidence as required to allow more experienced minds to come to, hopefully, the right conclusions.
I can go on and on here, but hopefully I've introduced myself sufficiently. I like the slant, always have. It's a engineering marvel for its day. So, I'm going to try to contribute here with my own journey into actually the first Mopar I've ever owned--always a GM guy back in the day, it's what dad drove, until he bought a 280ZX.
Returning to the header discussion now, concerning lack of intake preheat, condensation and lean mixture during cold operation, etc. Just out of curiosity, how do aftermarket intakes manage this problem, especially with headers? In other words, there's a solution somewhere, maybe it's not heat tape.
I did take a closer look at the Jeep header this morning, and noticed, now, that the exhaust ports are round, as you pointed out. So, yes, that claim was incorrect. Sounds like you're dead-set, and very possibly correct, about the manifold not working, so I'm not going argue otherwise. Sure anything can be made to fit, but at what cost of time and energy. I asked the question here, again, to tap expertise and save time.