Thanks RobH and Andy.

My MC21R with new top end rebuild and Jolly Moto exhausts feels weak/sluggish at bottom end till about 5000/6000 rpm and a big difference when I compare the low end/mid range power to my mc18 R2J with OEM chambers and Tyga silencers.

I think I will revert to the stock chambers with some aftermarket silencers as I truly miss low end /mid range acceleration.