If you are trying to solve a nuisance pop off problem, perhaps the issue is that the heated water has no place to expand to. The situation is that ALL public water suppliers (in the US) are starting to insstall double check valves at the water meter to prevent backflow from going into the main line in the street. Its called back flow prevention and its done to protect the water supply from contamination. However, with these check valves, your hosue plumbiing is a ‘closed system’. When the water is heated in the water heater, it expands and thus the pressure in the closed system goes up and many times exceeds the relief vlave pressure rating. Solution ? Install an accumulator tank on the cold water inlet to the water heater (between the tank and the shut off valve to the tank. You’ll pobably need to regulate the water pressure coming into the house to about 80psig max so the tank can work correctly. Supply house can help you with tank sizing.
I would NOT recommend using a water heater relief valve with a pressure rating greater than 150 psig. That gives a factor of safety of 2 (WH tanks are 300 psif tested). Going to a 200 psig valve reduces your factor fo safety to 1.5