from reading your interesting article, I understand that an engine with 4 valves that is running under 10k RPM isn't really necessary due to the friction, but it's great if you're above 10k RPM, right? So does that mean that the more RPM's you have, the less friction?

Does a three valve engine rev faster then a 4 valve system? If that's the case, then can you kindly explain how come Hondas rev so high and so fast?

Also, new MB cars all come with 3 valves, and the rest of the carmakers are either running 4 valves or either 5, like Audi. Why the difference? Any reply would be helpful. Thanks.