I understand and agree with HOHN, to a point. I can acheive max boost empty or towing. Well maybe I can squeeze out 1 more pound if I'm pulling a long hill towing but my rpms have to stay up. I also have a hard time reaching boost in 5th gear unless I'm really moving out. So I can assume that max boost is only going to be reached when I have a higher load on the engine and turning a higher rpm level.