Does a Surplus power steering pump Provides better pressure than a after market replacement pump?
Well I would go with a new part rather than rebuilt in my opinion only because you don’t know if it was rebuilt properly and also if it’s a junkyard part it may be cheaper but beware it may leak or not work at all, if I were you I would look into a quality brand when it comes to something like that.
Some car parts, you should only buy brand new. A hydraulic power steering pump is one of them.
Surplus? Do you mean a used one from a junkyard/recycler, or are you asking about Original Equipment Manufacturer one from a dealer vs an Amazon/AutoZone one? Either way, the pressure is probably pretty close, but you might have leaks from a recycled on, and a cheap, off-brand one may not last very long.
Surplus in our country means Used Power steering pump but directly coming from original stock. Is it better than those thailand made bnew replacement pumps but are not genuine Japan manafactured?
I think you're OK buying a surplus pump - if you can return it if it leaks. A lot of the cost/hassle it taking out the old one and putting in a new one, you don't want to do that twice AND pay for 2 used pumps.