Check out this YouTube video for the best explanation I have ever seen on the subject. It was originally produced in the 1930's and the full length version has some cool precision motorcycle riding to illustrate the concept at the beginning. Here is that link

http://www.youtube.com/watch?v=yYAw79386WI

If you want to get right to it without the intro, here is that link

http://www.youtube.com/watch?v=F40ZBDAG8-o

Let me know if you like these features and if you want to see more.

Thanks,

Gomer

Hey! Check out this article about exhaust.

http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm Helps to explain the science behind it along with some of the myths.Let me know what you think.

Gomer