It depends on how you want it to react to throttle input. I set mine up to kick in at ~80% throttle (an effort to control spike), but must guys do just the opposite especially if they have bigger turbos. An earlier turn on point helps it spool up faster.
First, I suggest you turn on the ignition and leave the engine off so the BSTC has power. Slowly apply throttle and note when the light comes on the BSTC. You can then adjust from there and you'll get the turn-on point based on how much pedal. Then you'll have to go for a few blasts to see how it works in action. Remember that the chip control of the boost solenoid remains whenever the light is off.
Scale. The scaling is used to back off boost in 3rd gear when the load is greatest and knock is more likely. The scaling knob backs off the boost as a percentage of the amount of boost dialed in OVER base. With a single solenoid, the BSTC can dial in 6lbs over the actuator pressure, and the scaling will be a % of that 6 lbs. As an example: If you have the stock unmodified actuator (~11lbs), and you set the front dial all the way up, then you should get about 17lbs (11 + 6) of boost. If you set the scaling adjuster to mid point (50%), then your boost should drop by 3 lbs to 14 in 3rd gear.
Clear as mud?
