You seem to be mixing terms when you refer to pressure relief and pressure regulator valves, but let's start at the beginning. First of all, 160 psi is about 3 times too high for inside a home. What is needed to control this is called a pressure regulator valve (PRV). This is a bell shaped brass device that is installed where the main supply line enters the home. This is adjustable and should be set around 60 psi. The T/P valve which I think you are calling pressure relief, is on the water heater. It protects the tank for runaway temperature and excessive pressure. Either of these conditions will cause the tank to explode like a bomb, so they are vital to the system. Now what is causes this valve to leak is the incoming water pressure is already above the 150 psi limit of the T/P, so the T/P is functioning normally. When you install the PRV and set it to 60 psi, that problem will be eliminated, but another problem will be created. Here's what happens. When water is heated, it expands. This water needs someplace to go. In a system that does not have a PRV, this expansion is just absorbed by the city main and there is not problem. This type of system is referred to as an "open system". However, a PRV has a check valve that prevents this expansion from getting into the city main so the pressure will raise and trip the T/P. This is called a "closed system. Fortunately there is an answer. An air charged canister with a bladder called a thermal expansion tank is installed between the water heater and the PRV. This tank is air charged to match the setting of the PRV and absorbs the expansion as needed. I should point out that some PRVs have a bypass to deal with the expansion, and some water meters have a check valve. So if your new PRV has a bypass, you will have to find out from the city if your meter has a check valve. Excessive pressure creates another potential problem. It is very hard on washer hoses, as well as valves and faucets. Just make sure if you end up with a Closed System that you install a thermal expansion tank.