Like my 1998 Moto Guzzi Centauro. In order to pass Emissions Testing for sale in the USA, the bike as sold had an ECU control ("ROM" that made the bike almost unrideable, but allowed them to pass testing.
When you bought the bike, you had to:
1) Replace the ECU program with one sold by quite a few back-door aftermarketers, usually via a Guzzi club or forum.
2) Replace the "colostomy bag" exhaust collector with a crossover pipe.
3) Replace the non-functional plastic cylinder head temperature holder with a brass one that actually conducted heat.
Once you did that, the bike's engine was a marvel of smoothness and power ... BUT it would never pass anyone's emission test, and was therefore illegal to use. I never heard of anyone getting tested, though. Rode mine 40,000 miles.
Just one more indicator that over-regulation makes outlaws out of all of us ...