So I just installed the AEM Tru-Boost gauge in my X. I plugged in my AP and went to the live monitor setting just to compare the results to the gauge. When the car is ideling, the Cobb reads -9 psi or so, while the gauge is reading -17 or so. Also, when I go full throttle, the Cobb always seems to read a little bit higher boost than the gauge. Which on is more accurate?

The way I ran the AEM is I T'ed off the line running from the manifold which then turns into a hardline and runs back to the firewall. Did I install it in a bad place? Thanks in advance.

 

The AP reads directly from the ECU which gets it's data from the 3.3 bar MAP sensor mounted directly to the intake manifold, this is the boost number I trust. They are reading vacuum differently though (your gauge reads it in in/Hg) so that's a fine # to look at even though it really doesn't mean anything for you.

 

Ahh, makes sense. So should I use the AP when tunning the EBC portion of the AEM, or is the gauge fine to use, you think?

 

Never hurts to go by whichever reads higher just as a little safety margin.