[Shazaam!]

Southern California, particularly around Los Angeles, has long had a severe air pollution problem because of the large number of vehicles, weather, and landscape topography. Over the years this has been a driving force for the State of California to institute more stringent exhaust emission standards than the rest of the U.S. So for a long time, there were two standards for pollution control equipment on vehicles sold here. One for vehicles sold in California, another less stringent one for the rest of the country. So, there are laws against a resident of California buying or importing a new bike that doesn't have emission equipment certified for California roads. Highly-polluting two-stroke bikes have long been outlawed on the roads here (they're legal for off-road use) although some enterprising blokes still get them on the road somehow.

In recent years Ducati has certified their models for sale in all the States so there's no equipment differences now. My guess is that most European countries have now instituted limits on motorcycle emissions that are the same as the U.S. since the manufacturers biggest market is here, so we essentially drive the standards development.

Motorcycles have always been regarded as a minor contributor to the overall magnitude of the problem. They produce fewer pollutants per mile than cars and trucks. But they're starting to get more attention from the regulators - witness the phasing-in of requirements for catalytic converters on new bikes like the 999.

So early Euro-spec superbikes, since they didn't have to meet any pollution standards, were shipped with different EPROMS that gave them richer fueling and more power than U.S. bikes. Some models had more radical cam timing that couldn't be certified for the U.S. market so you got those models, but we didn't.

The interesting part is that unlike automobiles and trucks, there's no tailpipe emission testing of motorcycles (yet) so it's illegal ... but no problem ... to replace EPROMs, raise compression ratios (higher NOx emissions). and remove charcoal canisters that trap evaporative hydrocarbons from the petrol tank and sump (although really there's no performance improvement in doing so.)

The other regulations concern noise emissions. The federal government's Environmental Protection Agency establishes limits on noise levels for every vehicle that's imported. So mufflers (silencers) and air intake noise reducers (like those rubber venturi blocks on late-model superbikes) are installed.

Automobiles and trucks are regularly scheduled to be tested for excessive exhaust noise in order to be licensed, but motorcycles as yet are not. So, if you get stopped for a traffic violation, you'll probably also get a fix-it ticket for defective equipment that gives you a month or so to quiet-down the exhaust. Consequently, the streets here are rich with Harleys having straight-through exhausts that sound like the HAMMERS OF HELL. Here in California, the ultimate car culture, every kid with a Honda Civic has an exhaust pipe the size of a coffee can. But I digress.