Will pressure drop if I replace a full bore valve with a full bore?

Hello. In this case, it is difficult to give a definite answer, not knowing the data on the current pressure in the water supply system, as well as the approximate scheme of the pipeline itself.

It is possible that the customer indicated a partial bore ball valve for a reason in his TK. Since these cranes are used not only for the purpose of saving metal, but also in order to reduce the moments and efforts required to control the valves. It is also worth noting that a non-full bore ball valve with respect to a full bore has a higher coefficient of hydraulic resistance.

From this we can conclude that one cannot just take and replace one faucet with another and at the same time rely on the correct operation of the water supply system and connected devices.