Or better yet - does anyone know the amp draw of a stock gsr fuel pump?

OR - does anyone happen to know the resistance of a known good stock fuel pump?

The wire chart looks like a 12 gauge line will be best, but a 14 gauge should do fine for the Bosch. The question is what is the stock wire size for the fuel pump?

 

You definitely should not use the stock line. Id stick with 12 or 10 gauge for the pump. The stock is like 16 awg I believe.