batman
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osceola new york
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It might pay to know that there are two components leaving the exhaust pipe ,exhaust gases which move more slowly, and a pressure wave that starts when the valve first opens that can travel at the speed of sound. It is this pressure wave that forms the basis for tuning the exhaust ,and the length of the header pipe. when the pressure wave reaches the end of the header it expands and moves backup the pipe as a negative pressure and if it arrives to find the exhaust valve open it can help pull out some of the remaining exhaust gases as well as pull in a fresh charge due to valve overlap . the return speed of the wave is slowed by the fact that as the gases move down the pipe they cool .Shorter pipes favor high rpm , which is why they were used on board trackers running at WOT. Using a stepped exhaust pipe increasing in size as it get farther from the head would allow the gases to expand and cool slowing the wave and might help in shorting the header length so it might work better at lower rpm , but the noise would ,without a muffler ,still be painful . As a test place the stock header on with no muffler and run the bike (wear ear plugs!) Running a "lollypop" baffle may help reduce mid range sag by breaking up the returning wave ,but overall performance will suffer.
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