Low Pressure in Price Pfister Valve- Faucet

Hey,

We had a tub/shower install a couple of months ago. We had the plumber install a Price Pfister- and we converted from the "older" style two handle with stems.

After the install, our water pressure there is remarkably lower, both in the showerhead and the faucet for the tub. Pressure is normal and the shutoff in the basement is fully opened.

I called the plumber who was not sure why the pressure would be so low- and I took off the handle, looked at the valve- everything seems in place. The water pressure is low enough that it flows down on the side of the tub rather than "out".

Any suggestions?

A restriction in the supply? What do you have for pipes?

Looks like copper? The lines put in when they redid were new.