I received a reply from DA, which unfortunately cannot be re-posted due to a confidentiality clause. However in my own words, what I will say is that they 100% stand by their claim of 100% US Manufacture. And from what I now know, it would seem the Chinese may have attempted to copy some of DA's products. But have done so with poor quality parts and materials, resulting in failures of some of the inferior copies. DA will 100% stand by their product warranty, and should any one have any problems it is recommended that the product is returned to DA.
I can't comment on anyone who has a pair of these Chinese copies, because I have not spoken to anyone with some. However I have spoken to a number of people who have the genuine DA ones. What I can say is that every one who installed them and did so in line with DA's instructions and used the recommended oil has nothing but total compliments about them. Unfortunately some people think they know best and ignored DA's instructions and did the installation their own way..... Those people may have found themselves unable to claim on the warranty.
My Car with all the stuff I've bought for it is worth over $20K...... I'm not about to take risks to save a few hundred bucks. I will fit mine in full compliance with DA's warranty. As such I have remained in contact with them to ensure each component used in the installation meets DA's requirements. You are more than welcome to note my user name and contact me in a couple of years, to find out how well they are doing.
Finally...... again in my own words. I rather got the feeling that if anyone wishes to Challenge DA's claim to manufacture their own turbo's in the USA. Perhaps such a person could do so to get their money back if they felt so inclined ??.... DA would be more than happy to meet such a person in a Court in Nevada where they are based. And if true, based upon the various comments in the link you posted, that should be easy money for anyone wishing to give it a try........

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Personally I'm very satisfied with my purchase. The quality is excellent, the customer service is equally excellent..... And I am satisfied with the fact that they ARE manufactured in the USA !.