Dudes,
A boost GAUGE would be connected after the throttle body. IE, the inlet manifold.
A boost CONTROLLER/wastegate would be connected before the throttle body.
A controller needs to open the wastegate to adjust the boost, so when you take your foot off the throttle, the pressure before the throttle body, will rise, because the throttle body will close and the turbo will still be pumping boost. So at this point the pressure after the throttle body will be bugger all (which is what you want your bosst gauge to read), but the boost before the throttle body will keep going up until the wastegate is opened. So you want your boost controller connected before the throttle body so that when the boost tries to go past what you have dialed into the settings, it will open the wastegate for you to prevent overboosting.
