You need both arms really mate, it's good you have a boost guage, it may take a good 3 or 4 times to get it set right, if you wind the actuator rod inwards it ups the boost, the more you wind the rod out it makes less boost. You will need to start it weak, take the car round the block see what it boosts like, you can then come back (wait for a long time or you will burn urself to fook on the turbo ) and adjust the rod again. Don't wind it right in and run silly boost Oh, and i'd suggest a good setup to check the fueling and get it rolling roaded to make sure all is ok by a top tuner