From the previous threads I had scanned before I started this one, you *MAY* be able put it on a stock flashed car safely, but definitely NOT a Cobb or Ecutek flashed car. Due to the more agressive WG duty cycle maps, I would assume, you will overboost or have spiking problems. That information was posted by reflash users, so I included the warning that you must retune.
I have run my car with the boost solenoid on a factory/stock flash and it runs fine. I seem to get a lot less boost, though, like 11-12psi. With the factory solenoid I'd actually get more boost, like 13-14. I'm not sure why I'd get less, but that's what I saw and I have logs of the behavior. The new solenoid certainly did not help spool or anything with the stock reflash. But it DID help a noticable amount with my UTEC. The spool and performance difference between the UTEC and stock mode is huge.
YMMV. I would watch your boost gauge no matter what.