I'm going to install the boost gauge on my car tomorrow. It's a little Scion tC and I'm not sure which vac line I should T into for the boost gauge. I was told any vac line should be fine but I was wondering what is the most common one to use. Thanks in advance for the help.

Any vacuum line that is connect directly to the intake manifold (after the TB) would be fine.
Is this the TRD SC?

>yeah. ive had it for a few months - i love it. although sometimes i wish it was a manual, but its still enough power to beat most economy cars on the street. lol.

theres a vac line going from the TB to the BPV and it's T'd off already - can i use that?

That one is OK too.