I also ordered a few extra elbow pieces for my extreme. went out and bought a nice Purps brand bong. Got a good price because i removed the ash catcher, i only use the bong for vaporization. never actual smoke.
i like to bubble through my lower quality herb , it removes the carbon monoxide and make for a smooth tasty vape. With the good stuff, i simply pack ice, allowing for bigger drags and it cools down a usually warm vapor.
the extreme elbow joints plug directly into a 18.8 mm bong. much cheaper than buying a "real" 18.8 mm whip attachment.