Yes I understand that it is adjustable, I believe the one I have runs from 6* to 15*, but even at 6* and putting the distributor back to 16* I'm still back at 22* with the can. Anything higher than 22* and my vacuum signal gets super erratic. So I have to ask, can the vacuum stay consistent with the can pushing my inital higher? Running the truck at 28* sounds like a bad idea. Am I wrong on this track of thinking?