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Discussion Starter #1
Ok, I have read ALL the debates on DRILLING the stock exhausts out for more sound. I was just thinking, if you drill into the end caps you are undoubtedly decreasing back pressure. but if you are Drilling into the baffle how would that decrease back pressure since the "OVERALL" opening is the same? I know it will be freer flowing but to me the back pressure should only slightly decrease doing this mod, where as if you drill into the end caps back pressure will significantly drop as you are increasing the total area of the exhaust hole.
 

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Exhaust back pressure isn't necessarily a condition or size of the exit point of the exhaust but also the volume of the can and the path in which the gases must move. A different path will create different pressure pulses and a smaller volume will build pressure more quickly with a smaller volume of gases, again changing the back pressure and of course the haromonics of the exhaust sound. Which is the point of most doing this, they want a different sound for no cost, IMO not a reasonable trade off . The changing of the pressure pulses can signifcantly affect the scaveging and the cylinder filling ability of the intake system. Almost never will it be for the better on a home "designed" system across the rpm range. Usually a change of this type "may" result in a wee bit more hp on the top but at a significant cost of torque and hp on the bottom end where the bikes are used most often.
 

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Discussion Starter #3
well

its would be easy to Mod the ehaust by welding on Tabs to increase the back pressure. Kind of like "Mice" for the older Jet engines..
 
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