I have the Comptech SC w/AC. I installed a digital boost gauge from Dakota digital last week. I'm getting a negative reading until high RPM's. Does the line from the FPR "suck" (like a vac line) until higher rpm's and boost?

 

Yep.

Your engine will naturally rev it's head off. So we have a throttle upstream to limit the amount of air that gets to it. So whenever the throttle is less than say 70% open the engine will be trying to draw more air than it's letting through. Hence vacuum.

 

Thanks Aus

I guess since the gauge is digital it's giving me a negative value (vac pressure) until 5-6K RPM. If the gauge were not digital (needle style), I guess it would just sit at 0 until boost came on.