Hi Josephau - I think I replied on that other forum too - the twin header pipes are mainly due to the position of the valves, and to allow them to clear the (single) frame down tube... as you say, they then combine into a single pipe that goes into a honking great box at the back...

Personally I can't see why a single silencer wouldn't offer the same if not better performance... the main reason for a twin silencer system (such as that on the CRF250 for example) is to give more sound absorption material for the same amount of exhaust flow...

If you are overly worried about noise (and hey, we all should be) then a more open single pipe should improve flow considerably over the (cat choked) stock system.

Hope that helps?

JennyMo xxx

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