ZEP 8 Report post Posted February 28, 2015 For several months I had a ear cap over the interior (cabin) resonator hole. At high revs I could still ear a irritating vibration over my beautiful Perrin exhaust sound. I bought from japanparts.com these caps that eliminate the first segment of the resonator circuit. Now I have the exhaust sound and the natural noise of the boxer (much better). In theory I got a little bit of better air admission volume. It seems to rev better than before but perhaps it´s the psychological effect. Share this post Link to post Share on other sites
