OK, I am getting in on this post a little late, and feel really bad, but thought I could offer one more tip that will help. (In fact I probably should have added this to the tips section a long time ago
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Remove the pipe, and clean the pipe mounting port inside the cylinder as well as the headpipe where the O-rings ride. Use carb cleaner on a rag (don't want carb cleaner inside the cylinder), or laquer thinner. Once cleaned, put a bead of high temp black silicon over the O-rings, and reinstall the pipe. Let it dry overnight, and viola, you instantly have more bottom end power. The reason is that since combustion continues upon exit of the exhaust gas, any loss of pressure at the head pipe with decrease the effect. At high RPM, no problem, but at low RPM, a noticable difference.
Now, you might be thinking that the next time you pull the pipe you have to deal with all the residual silicon. Not so, as it will peal right off the pipe, all ready for the next installment. Don't believe this will impact bottom end power? Try it first and let me know what you think. Heck, high temp silicon is only a few bucks, so the test is cheap.
Rick