I sure this has been answered some where but i have to ask again.
I just installed a boost gauge on my 6.5 TD Should i have constant boost or should it only be there when accelerating? I have 0 at idle and if i get on the gas it goes up to 12 but then when you put the cruise on it goes back to 0.

 

0-2 lbs on idle is normal
on the throtle is when you will build it the most
i push 10LBS with 850*EGT @70MPH

 

Boost is a result of teh enginew working, with little or no load on the engine you wont see any boost.

 

x2

 

x3 takes fuel to build boost. It's funny though, too much boost when not needed lowers mileage. Too little boost when more boost is needed lowers mileage....

 

If you need more power you'll need a reflash/rechip, you can add a fooler and get more boost/power with stock program up to about 10 psi then IAT starts climbing to defuel about 12+ psi.

Fooler is a potentiometed, or fixed resistor wired into the MAP sensor, to lie to PCM how much boost you are making above the programs expecatations so it won't deboost (open WG) or defuel.

Another method is building/buying a Turbo Master mech boost control, these are handy when a vac pump has died.

The ATT mentioned in another thread (non waste gated), is a better turbo than the GM-X turbos will allow more grunt without overboosting or high IAT issues, I removed the IC I had on mine since IAT is so much lower, I'll be adding WMI to manage 12+ PSI situations when towing, I'm running empty to 100 mph with only 9-10 psi boost.