I'm shopping for a electronic boost controller right now. I've had the Greddy Profec-B on my GSR and the Greddy Profec-B spec II on my WRX. I personally like the original Profec better for simplicity.

My question is: I have the factory boost gauge, can I tee into that vaccum line behind the guage for the control box for my boost controller? Will a tee that close to the guage cause uncalibrated boost readings?

Thanx.

 

In all honesty you would be better off keeping the tee close to the engine. I had the profec B on my car and didn't not like it. It seemed to require constant adjustment and had trouble controlling the boost properly. I ditched it in lieu of a HKS EVC and it was night and day. The EVC is so easy to adjust and keeps close to your settings well with weather change. Some people have had luck with the profec on the Evo and some have had nothing but trouble with it. I will say that I wouldn't trade mine for nothing.
The other advantage is all the vacuum hoses stay under the hood with the EVC.

 

I took my Profec off my GSR and put it on my EVO. It was much nicer on the GSR. It seems like it needs to be constantly adjusted with the weather. The peak hold is a liitle shakey too and I'm not too sure how to properly balance the boost.

 

I never really played with it but I believe it needs some type of restriction in the line. The EVC controller is restricted down and it works well. Stock uses restrictors and it's dead on.