0Mr. StealthBest Answer 11 years ago You must put it in the middle for the chain lift because otherwise the chain would get caught on the knobs in the middle of each green track piece. As for the rest of the track, you don't necessarily have to put the middle tubing on. I built the Screamin' Serpent without the middle piece and it worked fine. The middle tubing is more to reduce friction and have a more steady ride. If you have enough tubing, use it. If you don't, then you're still OK. Hope this Helps!