I hope this is not a repost....
This was forwarded to me by a friend of mine a month or so back...
This explains the Honda city engines (called Fit/Jazz in other countries, but the engine is the same) in great detail.
http://asia.vtec.net/Series/FitJazz/lseries/
An extract from the article:
"The i-DSI designs are exploiting state of the art technologies, misconceptions about it still abounds across the internet and many people simply fails to understand that preconceptions made based on the 8valve design as 'low-tech' are simply wrong and that the i-DSI engines are 8V for a very good reason."