AS said above, but with a little more detail. Testestretta literally means "narrow head" and it refers to the angle between the valve STEMS. This means that angle the valves poke into the cylinder is "flatter" and so the combustion chamber shape "squish band" can be modified to give different characertistics. The 'stretta engine is known to give better performance running at lower rpm, which theoretically makes it easier to manage for "town riding". In my experience, I think it does.
As also said above, they started it with the 998, but some 996's towarsd then end of that range also had it. All the 749/999 series have that type of engine.
There was a write up on it with diagrams on the Ducati site (in the tech section) but when I just went to get a link I found this
"Due to our constant work towards improving the appeal, richness and usability of the website, we apologise that this area is temporarily unavailable"
Always amuses me when they do that ... a bit like when the Ducati sales guy tried to convince me that ducati were improving the range by limiting the choice of colours to red, yellow and black! My bank also has a sign up saying to "improve the service for ALL our customers, you can only deposit x bags of coins per day". Anyway, I digress. It used to be there, it might be again one day.
