fknlol!
From what i know the only point of a purge valve is to purge air and vapour out of the lines so that the liquid nos fully fills the lines... Its basically only used (properly) by extremely high end drag cars which need every last bit of performance.
Most people who are into performance cars know this, so therefore when they see a dude in a stock looking R33 purging what appears to be nos, they instantly think -POSER- Your car doesnt need that mod for any reason other than to try to look cool.
To make matters worse, you're talking about putting a FAKE version of a pointless modification onto your car. Thats twice as bad!