Ha! I didn't think anyone even knew what the hell gabapentin (aka Neurontin right?) was. Never mixed it with Piracetam, but I remember it really potentiating benzos for me back in the day. I know that doesn't answer your question or help but I just had to comment after seeing someone mention Gabby's, as we used to so fondly refer to em as.
Just out of curiosity, if you are prescribed them, what are they rx'd to you for? Last I looked they could be rx'd for a whole slew of things.