Not completely correct, at higher temperatures pressure will begin to build even with good gaskets. Remember, pressure stops boiling, If it still has a EGR cooler intact it will try to boil the coolant.
Sorry but you are not completely correct Len. Besides being thermodynamically sound, it is proven on my system (and others). I do agree that you might see 1 psig increase (the volume/space increase due to any amount of "flash boiling" on a healthy EGR cooler surface is minimal), but that is all a normal system will produce.
Any appreciable boiling is prevented by proper heat transfer (which includes proper coolant flow) and the physical properties of the coolant. You need adequate contact time on the heat exchangers surface to flash boil and a healthy system just does not have much.
That being said, yes I can see where it is possible that SOME systems operate at temperatures high enough to flash boil more than a minimal amount of coolant on the walls of the heat exchangers, but even then (in most cases), the vapor will recondense as it mixes with the mainstream coolant flow.
I run the SRL+ tune and I get essentially no pressure build after doing the described procedure (1 psig is not enough to cause concern).
Lastly, pressure does not stop boiling, it simply elevates the boiling point. Normal back pressure only elevates it 15-20 C degrees IIRC (25 - 30 degrees F). That is not enough to drastically effect the design of heat removal from the EGR cooler that sees exhaust gas at 700 *C (1300 *F +). Remember, our systems are degas systems, not pressurized liquid systems. The normal pressure that our system operates at is less than 10 psig (8 psig typically) and not the 16 psig setpoint of the cap.