I have an 04 wrx, with few mods. I have the stock boost gauge, and at idle it reads -.06 MPa. As i accelerate, it will go up towards the positve section. Do i have a boost leak? or is a bad seal? Was tring to find this from anyone else, but no luck so far. Any answers would be great. Thanks.
I know it's mean but I kinda chuckled when I read the post... It's ok I was there not too long ago.
To further his answer, you sit in vacuum (inmg/mpa), and then start making boost (psi/bar) as you get on the gas. You'll sit at vacuum when cruising and at idle, and the only time you'll really go to positive boosting is when you're accelerating.
Like stated above, you car was apparently reading/running wrong for the previous 4 years. At idle it should read in the negative range of any boost gauge. Upon acceleration it will "build" boost and cross from vacuum (negative) to boost (positive pressure).