Drone free exhaust system-solved!!!!!!

[Borys]

Hope this helps with this issue.
Had my system nicely done recently but of course Ii did not happend without droning. Some probably experienced this at different noise levels. Measuring mine with frequency app was around 100mhz. So off I go to explore youtube and google. Solution I found was at US forums. Widely practiced and effective. Simply it is based on heimholz resonator and it carries a proper math behind it. Around forums they call it "j pipe". Now there isn't a garage in a UK does it!! Which puzzles me as being an exhaust shop owner surely would like to have a solution at hand. I guarantee there isn't a system with after market boxes, straight pipes with out a drone. On topic. Car was buzzing/droning beetwen 1100rpm to 2000rpm. That range is commonly affected. With help from US forum calculation was made. J pipe to install needed to be 30" long to get rid of the drone across affected rpm range. This is a nice video explaining drone
https://m.youtube.com/watch?v=cILip2l0J6o
And where to place it
https://m.youtube.com/watch?v=afwdv3Qwdpk

Made a trip to exhaust shop made my set up. I prepared a presentation like for high paid job interview and owner agreed to try it. We installed the pipe at the back of the exhaust where the muffler usually sits. If I knew this before we would design a totally different pipe work. Its not a neat job as on the rest of the system as it has been done for the first time.

I don't think guys at shop believed that this will work.....test drive and boom no drone whatsoever only sound is left is a perfect v8 burble.
Just to add j pipe will not affect the sound it will eliminate sound waves which cause the drone. Also it can be any shape
Welcome to a drone free system!!!!!