Check out this link - its pretty technical and a little on the dry side - but I suggest my commercial students read it... It deffinitly helps shed some light on it....
Why Manifold pressure sucks! -
http://www.avweb.com/news/columns/182081-1.html
Here's a good one on the prop too -
Lots of info on large recip props etc, but a lot of the basic principles are the same
http://www.avweb.com/news/columns/182082-1.html