Vacumn source for boost gauge?

[spooltime]

Can anyone share some information on the best location in 955 Cayenne Turbo's vacumn lines to splice in a T-fitting as a source for an aftermarket boost gauge?  The factory gauge seems like it doesn't give a full reading and is reading off a sensor, not actual boost, anyway.  I'd like to install a more accurate boost gauge.

[hahnmgh63]

If you remove the center plastic trim panel at the back of the engine there are two vacuum lines that plug into the back of the manifold. One goes to the N75 Boost control valve and the other larger line uses one of those snap plugs but right off hand I can't remember where that one.

Over on Rennlist the guy Lupo who is trying to get almost 700hp out of his CTTS may know. I would imagine trying to tune for that much power you would install a Boost gauge. The stock one is probably electronic from the ECU/Map sensor.

Edited January 8, 2015 by hahnmgh63

[spooltime]

In poking around various tuning forums, one suggestion is that a more accurate reading can be obtained by tapping the "Y" intake plenum in front of the throttle body.  I wonder if that makes more sense than installing a T adapter into a vacuum line coming off the rear of the intake?  The pressure and air temperature sensor for the DME is located on the top side of the "Y" plenum, if that matters.  Thoughts?

[hahnmgh63]

I believe one of the main reasons to tap into the intake manifold (after the throttle body) is that you can have a gauge that reads the Boost but also reads the vacuum off boost from behind the throttle plate.