That 'rubbling' noise you describe it as is most likely 'det' where it's running way too much boost.....don't drive it hard until you've sorted the boost issue as you'll end up melting something! Depending on how much preload the actuator has try bypassing the amal valve by running one piece of hose between the compressor housing outlet and the actuator, and see what boost it runs then. Garages....most can't be trusted lol