Aaron, yes, that's what I'm talking about also: An independent shop using software to reprogram the fuel delivery of the injectors on, say, a Kioti CK3510SE HST, to achieve the hp of a Kioti CK4010SE HST. Both tractors are in the same series, are Tier IV compliant, and, I think, are otherwise identical in all material respects, except for decals and price point. Such a mod would not defeat any part of the emission/pollution control system, as far as I can see. And, afterwards, the CK3510SE HST would still be just as Tier IV compliant as the CK4010SE HST, wouldn't it? :scratchchin: I can see how it would be different if the modified tractor was originally exempt from Tier IV compliance or some other legal requirement because of its low hp rating, and the modification increases the hp beyond the exempt rating.
I'm a lifetime learner, and only generally familiar with the Clean Air Act, so if that's the law you have in mind, I would like to learn more about how it specifically could make the first situation unlawful.
This is really just a curiosity for me, as I'm quite happy with the hp of the tractors I have. But I think many of the current manufacturers are similarly derating identical engines solely for pricing/marketing reasons, so I suspect a lot of CUT owners would be interested in this discussion.
Thanks for the link to the article on hotrod.com. As I read it, though, the EPA enforcement action reported there only involved the prohibition of "defeat devices" that modify emission and pollution controls. No question that that's unlawful.