HKS silently discontinued their “catless” downpipes in the U.S. around 2021 for mentioned reasons above.
The loophole is that it doesn’t apply if you never take it off private property.
You can't modify the factory emissions output to go below the required output.
People like the Diesel Brothers from the Discovery Channel settled for like $3 million USD with the EPA for selling and promoting emissions defeat devices like tunes and straight pipes.
I or a family member has acquired a few vehicles where the catalytic converter was cut out by thieves, and I've done both so I can tell you from experience that it's the difference between $15 and $800 (parts and labor).
Having grown up extremely poor, sometimes families make those decisions because they don't really have a choice. Thankfully nowadays I do so I tend to err on the side of being a good citizen but personally will not judge anyone who choose s to weld a pipe in place rather than spend the exorbitant amount necessary to replace it, especially considering it might just get stolen again.
How does a manufacturer enforce the use of a device in that way?
"The Clean Air Act does not contemplate removing emissions controls from an EPA-certified motor vehicle in order to convert it into a competition vehicle. As a matter of enforcement discretion, the EPA’s longstanding practice has been not to take enforcement action against vehicle owners for removing or defeating the emission controls of their EPA-certified motor vehicles, so long as they can show the vehicles are used solely for competition events and no longer driven on public roads."
https://www.autoweek.com/news/industry-news/a36482793/sema-e...
A lot of the big name exhaust companies have stopped producing catless products; and others require all of your information to be on file if you’re buying a catless race downpipe.
A lot of the install shops around here in Maryland that run a legit receipt paper trail of work type of business won’t even touch catless installs anymore.