Recently I changed the on off valves and hoses below the bathroom sink for both my hot and cold water. Now the pressure is really low. Am looking for answer to this puzzle. I checked hoses and valves to ensure no obstructions. Advise? Thanks

Have you checked the aerator on the end of the faucet spout, the fine mesh screen could be stopped up, espceially if you used a liquid pipe dope in putting the fittings back together.

Unscrew it and look it over carefully. Even turn the water on with the aerator off and see if the pressure of volume is better.

Follow letmetellus advice about checking the aerator ,(see image ) first. With the aerator removed turn the water on. You should have a strong stream.. If not then you've disturbed some mineral built up on the pipe walls and it's now blocking your cartridge. Shut the water off and open up the valve. Pull the cartridge out and check and clear the inlet ports. Now place a pan over the valve and turn the water back on to flush out the supplies. Reassemble and test. Better now? Good luck, Tom