I'm looking into getting an A-pillar gauge pod, and i wanted to put a boost gauge, and A/F gauge, and an oil pressure gauge in there. I was thinking i'd go with stewart warner, since i've heard some good things about them, and i've heard not so good things about Autometer, as far as boost gauges are concerned. But i'm really not sure what to get for the boost gauge... do i want a boost gauge that shows 0-15 psi, or a vacuum/boost gauge that shows 30 vacuum to 15psi?? I don't really know much about what vacuum is, why it occurs, or if its important to monitor.... ?? I'm pretty unexperienced with this stuff. Any suggestions greatly appreciated.