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Burns - The header/collector concept works because the longer pipes are "tuned" for the pulse reversion to assist the scavenging of that same cylinder. This would not create a negative pressure wave in the other cylinders because the pulse wave in the collector is a pressure pulse. The pulse, regardless of whether it is above or below atmospheric, will follow the inside diameter of the pipe that is carrying it. Once a cylinder pulse (above atmospheric) leaves the individual tube and emerges into the collector, the pulse (still above atmospheric) is now travelling along the wall of the collector. The pulse is unable to revert back down the other tubes because of destructive interference of diameter 1 (the runner) and diameter 2 (the collector). The first diameter change after the runner (D1 -> D2) is where the tuning reversion pulse originates, once the pulse enters the collector no additonal benefit may be achieved from this individual pulse. Automobiles use headers because they provide additional runner length over a cast iron manifold. The tubes run together and into a collector so that a muffler and tailpipes may be easily attached. Now with all of that being said, IF the product that Denny sells DOES make additional horsepower (?), it is most likely because you are strictly adding length to the exhaust system. The extra length might bring the resonant tuning frequency of your exhaust piping system closer to that required for your particular tractor, at a particular RPM. The resonant tuning frequency requirement would be based on the RPM and number of cylinders of your engine. It WOULD NOT be due to the dingus (torque pipe, whatever) itself enhancing the pulse tuning of your exhaust system. My guess would be that if it is adding horsepower, then a piece of straight exhaust pipe appriximately the same length would do as much, if not more.... Goldsburg P.S I have never dyno tested the Torque Pipe. I have never believed in the concept enough to potentially waste $40.00
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