Kitchen Faucet pressure drop

I'm wondering what is "normal" for pressure/volume drop in a kitchen faucet? I have 1/2" pipe feeding the kitchen sink and the pressure is 40-50 psi. My original faucet (a Price Pfister 2-handle) never had seemed to flow more than about 40% of the water available, as if it's just pouring out with limited pressure. Today I installed a Tuscany single handle and the flow even seems worse. I suspect that much of the loss in both cases is caused by the reduction of the "pipe" size within the valve cartridge.

I have no problems getting 5 gpm from pipe at the shut-off valve, with great pressure. Is my problem merely the "cheap" faucets or am I missing something?

p.s. - The aerator is new and spotless.

Most of that is federally mandated...they limit the flow. I think it's in the area of 2.5gpm and lower for a vanity faucet. The only unrestricted valve is for the tub, but not for the shower. Well, those for a washing machine are not restricted, either.