The Stock GN (read: OEM) baffled tank is VERY capable of puting a GN into the 10's. The only real upgrade needed is the Walbro 340, and a Hot-Wire, or Plug-n-Play kit.
I don't know what the FASTEST a GN has run, using the factory tank, but I know of a few high 10 sec. GN's that still have the Stock tank.
Ryan