Hello. 5psi is about right, but, obviously, 1 is too low. But, if the car can keep running at higher RPMs when it's warmed up, I would suspect that the gauge is not telling me the truth. I have heard that those gauges from Summit read a little low when they get warmed up, but, I do not know this to be a fact. I think that I would call the Summit tech people and see what they had to say about this.