Changed it last night and it was smooth. Yes they come with like 200 psi and then need to tighten the nut to get the desired psi. Also noticed the difference between the gun handled trigged or not is less than 50 psi which is perfect.
It was more challenging to find a good spot to remove this piece. I should have taken a pic but right after the top part of the regulator ( L shape brass thing), there is a fitting which screws to a swivel from other side. Loosened the swivel and removed, then unscrewed the regulator form the button, put the regulator on a vice and removed the top part fitting which was screwed to the L shape thing, and then reversed all these on the new regulator. Probably too much details for folks with years of experience but useful to newbies.