As far as I know he said he had to smoke test two ways, from two different locations in the engine bay, I just can't remember the locations. One for vacuum, and the other for brake, I think

something like that. He put 15psi through it, and the smoke was coming up above the dipstick and around the gap in between the metal plate that fixes to the inlet manifold and radiator. He first thought it was the intercooler, (I have a side mount oem) we checked the plastic pipes, like the cold air feed and the other one in the location in front of the dipstick, but it wasn't these. After this he blocked off the top of the dipstick tube with his thumb, which seemed to stop as much smoke, and that was his diagnosis. The smoke is not always that easy to see though, as you need a bright light or a uv light to spot it.