Friend of mine had one of those boost guages. It always read 2psi less than actual. You get what you pay for. I'd rather stick with a known brand like VDO, Autometer, etc.
thanks for the suggestions, you have saved me grief, i have a vdo gauge and it's a vision series which is supposed to be nice and it always read low. at 0 psi it read likes -1 or 2