no prob, oddly enough, a few people were asking about it at the same time.
what people forget is that the sensors that control the boost get their measurements from the intake manifold or near the intake manifold.
for example, to make 15 psi, assuming 1psi loss at the intercooler and 2 psi loss from a boost leak, your turbo has to make 18 psi instead of 16 psi. You're operating out of your intended efficiency area and creating excess heat, further reducing power and efficiency. 15 psi at 130 degrees is not as dense as 15 psi at 100 degrees.
I just thought of 1 leak I had that a leak test wouldn't have turned up...the mk3 cars have a vacuum tube inside the ecu that always splits and shows up as a "bad ecu". The tube is part of the line that goes from the pressure sensor inside the ecu to the intake tubing.
You won't be able to hear it because the leak is inside the ecu. The split is so small and the sound is masked because it's inside a metal box...that would be a PITA to find if you didn't know about it.
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