There is a little metal restrictor in the pipe that runs from the plenum to the T piece (pipe no 5 on the diagram shown previously). The pipe has a green band round it where this should be. If this isn't there, the boost will be lower.
Once you have confirmed this is there, remove pipe no 6 from the 3 way connector, leave the other end alone. Then remove pipe no 8 from the solenoid valve, leave the other end alone. Connect pipe no 6 to where you just removed pipe no 8 on the solenoid valve. Make sure it's a tight fit, if not use a cable tie to make it air tight. If it's still not tight, substitute hose no 6 with a tight fitting silicon pipe. Then, connect pipe no 8 to the 3 way connector where, you removed pipe no 6 from. Job done. All connections must be air tight. If they aren't, you will lose vacumn and boost.
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