I have a extra power steering pump for my 99 RS left over from an engine swap. I am wondering if anyone is aware of any sort of mod that can be done to the pump its self to change the steering characteristics?
If you are talking about changing the way the steering feels, the best way of doing that is changing the characteristics of the servo valve. The easiest way to change that "feel" is to change the torsion bar inside of the steering servo. The pump only provides power steering fluid to the servo (and robs power).