Thanks for that input, Jape.

The stock JH600 is a very quiet-running bike and as of July 1 is certified to meet China's latest emissions requirements, which are pretty strict. China's emission regime is roughly analogous to Europe's, and Beijing has committed to a schedule of escalating restrictions on emissions, just as Europe has. I can't find specific references this morning, but I recall that on July 1 2010, the emission standard known as National No. 4 came into effect in major cities. This standard supposedly exceeds Euro III, which is in place for motorcycles in Europe until mid-2012, when I believe Euro IV kicks in.

For this reason, Chinese motor vehicle regulations are relatively strict, and, in the Chinese way, the system seeks to ban modifications rather than subject modified bikes to standard tests. This is why we are concerned about our muffler mods, especially in cities like Beijing which have a reputation for inflexible enforcement. Though Shanghai's inspections are more lenient, I'm keeping my stock bazooka in a closet just in case I have to put it back on to pass my two-year inspection.

So in this context, in which manufacturers are under pressure to comply with strict emissions and noise restrictions, it's a safe bet that performance will take a back seat. The factories want their bikes to pass inspections, and will do what it takes. Hopefully, this means that these tailpipe and muffler mods that we are playing with will actually improve the performance of the engines without throwing engine control functions too badly out of whack. We are aware that they will undermine emissions controls and noise suppression to some degree.

Calculated risk, both with engine function and regulators!