The EPA has retracted language that would have required race vehicles to be EPA-compliant and forced superbike racing series like MotoAmerica to scrap their rule books.
A new statement issued by the EPA says that the agency's focus is on manufacturers making devices "for competition use only" that are actually used on street vehicles, not on true race vehicles. The previous statement from the EPA would have required that any race car or motorcycle that was originally an EPA-certified vehicle would have to remain in its certified configuration, even for racing. Since superbikes in the MotoAmerica series must be based on street bikes, but are highly modified, they would have been illegal. Legislation was filed in Congress to counteract EPA plans to regulate competition vehicles.
The new statement from the EPA states that the agency "supports motorsports and its contributions to the American economy and communities all across the country. EPA's focus is not on vehicles built or used exclusively for racing, but on companies that don't play by the rules and that make and sell products that disable pollution controls on motor vehicles used on public roads. These unlawful defeat devices pump dangerous and illegal pollution into the air we breathe."
So the EPA is fine with your true race bike or modified track-day bike (as long as you don't ride it on the street). As for that street bike you stripped of the catalytic converter, well, that's another matter.