R5K, MC21, and MC28 silencers are increasingly restrictive model-on-model, so a set of silencers is well worth fitting. If still available, I can highly recommend Swarbrick carbon silencers for a direct fit to standard MC21 chambers.
The key benefits of aftermarket chambers are weight saving and over-rev. Race systems generally produce peak power around 11,500rpm, and will over-rev beyond 12,000rpm (inadvisable!), whereas peak with standard exhausts is often closer to 10,800rpm. Delimiiting the airbox will free the motor up somewhat more.
Standard chambers absolutely destroy race pipes in the bottom-end and mid-range!
This graph shows a well-maintained, stock delimited MC21R with Swarbrick silencers before and after our airbox mod.
However, a race system (both chambers, cans -- even alloy ones, and manifolds) weigh less than one bare stock chamber.
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Andy.
NSR-WORLD.COM
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