Well by his own admission on his website, he has sold out all his 2012 production. As for a private residence, I think if you operate a buisness that involves a federally regulated product, I think the federal agency that regulates that activity can come and visit anytime they want. They don't need a warrant, as you are participating in the regulated activity. They don't much care that you may or may not live at your place of buisness. Ask a gun dealer/manufacturer who operates out of his garage, or a fisherman that participates in a federally regulated fishery from his live-aboard fishing vessel...
By the threatening tone of his video message directed at this forum, I am guessing that if the EPA did come visit him, it wasn't as rosey a visit as he portrays... And if they didn't come visit, why the video? Probably a cease and desist order and or fines untill compliance with current tier requirements is demonstrated. Similar to what they applied to pepboys or shucks/orielys, or whatever the large chain store was that got popped for selling non-compliant chinese engined power equipment a year or two back.
As was shown a few years ago by at least one individual that tried to get the roid to meet the EPA's ever rising hurdle, it was going to cost several hundred thousand dollars to just perform the laboratory testing for each tier hurdle, letalone pay for the engine R&D or apply and pay for the certification/liscence. If I recall correctly, he had to either buy the equipment to test the system himself, or pay for it to be tested just to make sure it works. Then when he applied for the liscence, he had to pay for the independent lab that the government chose to evaluate his application and the correctness of his claims that the modified engine meets emission specifications. Not anywhere near enough marketplace for a lower quality antiquated diesel engine to warrent the cost and effort to continue to import/modify.
The EPA wants the "dirty" diesel gone, of course not taking into account that virtually EVERY product we consume is in some fashion produced, processed or transported with one...