Old thread, but for any guys still buying these, the plenum is probably not the best place to get the pressure feed from, and it evidently makes the lines a bit too long. I just installed this unit into my car and the solenoid looks like this:
The feed comes from the intercooler return pipe so the engine will be seeing exactly the set boost, accounting for the pressure drop across the intercooler. The only possible problem i can think of is a leak between the turbo and IC, in which case the only warning sign would be the sound of stuff breaking. I'm not pushing the stock turbo hard though, i'd probably recommend getting the feed from just after the compressor if you're going to run it on the edge..