I think AGR used to be a great company when they first started doing there thing over 10 years ago. And they might still be a great company, but the product seems like it isn't what it used to be. Maybe even a little overrated.
My AGR Super Box got fairly sloppy in limited use with 35 and then 37" tires. I never had any problems with the pump however.
For my future steering needs I will likely consider PSC products or West Texas Offroad.
Here is a link on upgrading Saginaw pump from West Texas' website. http://westtexasoffroad.homestead.com/powersteering.html