your question about pressure is simple. increase the pressure in the house and you will increase the pressure in your shower. what i really think you want is an increase in WATER VOLUME. remove your shower head and look into the hole where the shower arm was. do you see the water restrictor? it should look like a button with only one (very small) hole. remove it and throw it away if you want alot of water and are not concerned about wasting water. if you have kids like me who stand in the shower all day, drill the hole slightly larger. hope i helped, js