What is this part?
 

What does this part do? Can I remove it from the plumbing? I guess it's a bias value of some sort?

http://i219.photobucket.com/albums/c...ps537dc1f9.jpg

From looking at the manual I think it is a proportioning valve.

The data in the manual says the split point is 284 PSI with a reducing ratio of 0.4. Presumably this is to the rear.

I guess I can pull it off and put on my own adjustable proportioning valve.