You should not touch the screw in the top. That is pre-set from Turbonetics and is to seat the spring pressure inside the wastegate, not the boost. Do yourself a favor and make a homemade boost controller. You can even run it in your car if you wish. Here's what you do.
Connect the side barb from the wastegate and the barb off of the turbo to a T connection. Connect another line off of the T and into the inlet port of a SMALL air compressor regulator. You can buy one from Home Depot or any other hardware store. Next, connect the outlet port of the regulator to the top barb on the wastegate. To adjust boost, start by turning the knob on the controller counter-clockwise and see where your boost is at. It should be 5 to 7psi. Then, Slowly crank the knob clockwise until the disired boost level is aquired. See, the less boost going to the top port in the wastegate, the less boost you will have.
If you have adjusted the set screw, back it off, then turn it in until you feel the screw hit the plate inside. Then give it one turn and leave it alone.
Hope this helps.
