the dash one is piped from the brake servo unit, there is a pipe that comes from the inlet to a T adaptor, from there a big pipe goes to the brake servo, and a little one goes off to the right along the back of the engine bay, it then goes into a brown round plastic "thingy" and then continues to the boost sensor below the windscreen wiper motor, its quite a big ish black box on a bracket, if you look it does have boost sensor stamped on it.
mine had a naff pipe going on the brown round thingy.
boost gauge needs to be piped between the Throttle butterfly and the engine, basicly on the inlet manfold, so it measures boost and vacum.
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