I just installed an Autometer boost guage on my SC. With the engine off, the guage is at 5 vacuum. Once I start it up it goes down to around 20 vacuum, and when I step on the gas it goes to about 3 vacuum. It is never reading a boost level, just vacuum. It seems to be moving correctly when I step on the gas it stays at about 3 vacuum, and when I let off the gas or let it idle it goes down to around 20 vacuum. But shouldn't it be reading 8 psi, instead of 2 vacuum?