The Titan guage is an actual pressure guage, not just an idiot-light-like guage that's just there to show you have pressure, but not register the level of pressure. It reacts to the extremes of what the engine actually sees. When you start it, or floor the gas pedal, the guage will spike. This is normal. You obviously don't want it to stay there, but when you put the engine under severe load, the oil pressure has to go up.
when cold the oil is thicker, therefore will show higher pressure, as it warms up the oil pressure will typically linger around the halfway point. I've always run M1 0w-40 and when cold the oil pressure will hit about 3/4 with moderate rpm's until warm. If the oil pressure pegs out, thats not good as there cerainly is a restriction in flow pressent or a faulty pressure sender. Of course before getting on it, make sure the pressure has stabalized, typically it takes 15minutes+ after the coolent temp reaches normal before the oil reaches operating temp.