So, my Wesitec tuned and upgrade GLA45 was having power issues. My boost is peaking about 25psi and then drops off to about 22psi while still WOT. Has anyone had any issues with the Wastegate? Weistec wants me to do a vacuum test on the wastegate to test it, but I am not sure how to go about that. They say you can't buy it separately from the Turbo from MB. Mamba makes one, has anyone tried them?