to do this drill about 3/4" deep with a drill set up for the tap size you want either 1/8 or 1/4. with your hole about 3/4" deep take a 1/8" drill and angle it to the inside of the manifold. now drill your small hole for the boost and vaccum to go to, then use a pipe tap and tap the hole for your fitting, done.(this needs to be done off the car and make sure you get the drill fillings out of the intake manifold.
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jim
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