Turbo Gauges

im a total newbie when it comes to car but i want to learn alot like mods and stuff... anyways right now im tring to figure out what the vac and psi mean on the turbo gauges... does it mean when psi is high it has high pressure meaning its pushing more air into the valves meaning more boost and when the brake is press the pressure is release and a vac forms and the high the vac the stronger the braking force? this is just what i thought it meant please correct me if im wrong and i was wondering whats the normal psi and vac if turbo kit was not installed...

ps are all gauges are useless but for looks?

thanks

Well the boost side or PSI is when the turbo is boosting and pushing air into the cylinders. It is measured in PSI or pounds per square inch. So if the needle is at 6 on the boost side you are producing 6 pounds of boost. Now on the vac side is just when the turbo is sucking in exhaust getting ready to boost. So you have the general idea.

As for the accuracy of the gauges I found the GTC's to be quite accurate, but I would never trust a stock one for tuning purposes.

Just know this: AutoMeter = AutoCrap. My boost gauge looked like it was working perfectly until I noticed my turbo wasn't pulling as hard as it was reading. I bought a brand new SPI gauge and discovered it was reading 2psi over what the acutal boost was. What a piece of shit. Now I'm haulin ass and know what my boost pressure is.