Gen3 Where to connect vacuum line gauge?

[SSINZ]

Hi guys, OK I am having a little bit of trouble trying to work out where the link my new vacuum gauge, vacuum line to? i have a ls1 engine and i can see that it might be possible to run it in to one of the air ports at the throttle body using a T piece joiner but I'm not sure or weather it will give a good reading or not. the gauge is for show but i want it to work! anyone with any ideas or have put this gauge on there ls1? pictures and desc would be great!!! thanks

[OFF T4P]

there is a small line that comes out of the back of the manifold and goes into the heater inside through the firewall use a t piece and join it in below the little white and black one way valve.