[HayZee518]

in my shower I made a boo-boo. too late to correct. I fed the system with 1/2 copper and installed a T then a drop elbow in my shower ceiling - one head at each end. I should have fed the valve with 3/4, then out the valve with 3/4 and then reduced to 1/2". I do experience a pressure drop at the remote end but I can live with it. I do feed the hot water tank with 3/4 copper off the main line. yeah 3/4 to both valves should be ok.
transition what you can with the tubing avoiding fittings if you can afford it. there's a slight pressure drop at fittings