Are you sure they where running into the stacks? I love the pulling crowd and im looking into doing a show this summer saying i dont start college till later now. Ive seen some trucks with tanks in the back. One looks like a bbq tank and that is the Propane injection. The second is either methinol injection or Boost cool? Not sure on it. One guy had a straight up cooler with two hoses running out of it going towards the front. Anything to help cool the motors the better. Im still kind of new to the pulling stuff, but im pretty sure the warmer the fuel and the cooler the motor= more power. Correct me if im wrong.