Removed the new intercooler and refitted the original one. I have a 1 bar boost spring in the waistgate. 2 test drives now with and without overboost switch connected. First run 1st gear boost cutout at 0.6 bar. 2nd run cutout the same with brand new overboost switch connected. I connected an air supply to the waistgate sensor hose and introduced air, 0.1 bar I could hear air coming from the waistgate. The more air i introduce the more escapes. from 0.1 bar to past 1.0 bar.