My factory gauge reads vacuum just fine but won't register boost over 1.2 lbs of boost. I've hooked up a mechanical boost gauge and it reads 11 lbs on the nose at WOT but the gauge cluster reads 1.1-1.2 lbs the entire time. It fluctuates the vacuum as you would expect and seems plenty responsive when in vacuum but just wont read the boost. Maybe this is how it is supposed to work, but why call it a boost/vacuum gauge on the cluster? Do the ecoboost cars read boost just fine? Is it a sensor issue with the GT's? Do I need an ecoboost map sensor for it to work? Is it just busted? I haven't the foggiest... Not that it's the end of the world, I would just like to know when/if the belt starts to slip and needs to be replaced. I was out wailing on the car Saturday and just really noticed it.