Im already having problems with my power steering.. still undetermined what the problem is but i want to order an underdrive pulley. Will this affect my power steering pump at all? sounds like a dumb question but yeah thats why im asking.

 

in a sense it could because it will be turning the power steering pump slower but it isnt enough to notice

 

You can notice it with large tires. A power steering flush (MERCON V only. please) wouldn't hurt.