No matter what, you cannot get rid of all flow restrictions from an exhaust system, so there will always be some backpressure. When the exhaust port is open and the periphereal port is open, that exhaust pressure will fill any volume at a lower pressure... so into the low pressure periphereal ports, regardless of whether or not the port is actually flowing. When the exhaust port closes, these exhaust gases in the periphereal ports will be drawn in, even with the periphereal ports closed.

 

The title of the book is:

How to tune and modify Engine Management Systems. By Jeff Hartman


VERY LITTLE INFO on Haltech, microtech and rotaries.

 

That's the one. As I said, basic info only, but its a start.