water flow rate

I have a new delta 1755 shower and tub faucet and I am not happy with the flow rate. I know that the flow is regulated by the valve, but I would like to know if there is any way to increase the flow by altering the valve? I have plenty of pressure and there is nothing in the line retricting the flow, so I know it's just the valve. Please let me know what options I have.

I just installed a Moen shower valve that had a restriction in the valve. It was in the line that diverted the flow from the tub outlet to the shower outlet. I was able to drill out (enlarge) the passage without any other effect on the valve.

You could also examine the shower head to see if there is any restriction that could be removed. That would be the first place to try.

Your valve is a "spout diverter" model. If you are interested in the shower and not concerned about the tub, you might invert the control valve so the tub outlet goes to the shower. There is usually no restriction in the tub outlet. Warning: I have never done that. It could cause water to come out the shower when you are trying to fill the tub.

valve

Drilling the ports larger could damage the valve. And the restriction is probably in the operating cartridge anyway, not the brass body. Inverting the valve, which is not always possible and still keep everything oriented properly, will only work for a shower only situation.