@Diploman; I followed your recommendation and spent the last 1-2 hrs studying the RC 390 "Exhaust development work" thread. (We can now we're retired). That is some amazing R&D and absolutely nails what you have been telling everyone. "The stock (2013-16) exhaust is a masterful work of very complex engineering". My interest isn't sound or power it is weight. I would like to get rid of the cat which is heavy and not required by legislation down here. Having read Formula 390's comments on his decatting experience I accept that's in the too hard basket for me. Going for a lighter product using the existing geometry just increases noise with zero performance gain and more likely performance decrease. What is really interesting is that the 2017 has this additional exhaust, clearly to meet Euro legislation, that can only be detrimental to performance and detracts from the original design genius..
