If you simply want to lower the boost, just undo the actuator (held on by a small circlip) and wind the bar so it's a bit longer. This is done from under the car. Make it so the bar is just too short to fit back on, should be about 1/2 a hole out so you have to pull the bar to hook it back over. I know this sounds confusing but when you get under the car and have a look it will become a lot clearer