How accurate are wastegate springs? Is there an easy way to test how many lbs they are at when they bleed off? I have a compressor but I don't think it's gauge is meant to be accurate enough for something like that.

 

A spring is less accurate, less reliable, and faster wearing than an electronic pressure transducer, if that is what you are asking. And that would be a great way to test your spring pressure would be to compare it with an electronic sensor.

 

No reason you can't use a shop compressor to measure when it vents. If your compressor gauge isn't accurate enough then use your cars boost gauge.