I bought a large Flash 3 (Euro, with Fatty OPI DLR80) this week but I found the sitting position a little uncomfortable for me (and I don't have the chance to buy the medium one) so I was wondering what's the shortest stem I can find for a headshok. It has a headshok C2 stem on it now.

There's a "Cannondale Headshok XC3F 31.8mm 80mm 5D Mtb Stem" in ebay, can I find a shorter one or should I settle for this stem? What would be the weight difference between C2 and XC3F?

Thanks in advance...