Other than the vaguest possibility of a carbon reed passing through the cylinder and out of the exhaust should it fail where an OEM fibre one could possibly not do the same thing, I've never personally seen anything to convince me that aftermarket items are worth the money. The HRC rectifiers however, do appear to make a noticeable difference on the MC21 and MC28 on the dyno, but again it's not necessarily something you can physically feel.
Maybe back in the days when bikes like RD's had metal reeds they were worth playing with, but I run Honda/HRC reeds as does the most powerful NSR250 in the UK. If either made significant gains replacing the reeds with carbon ones I'd eat my own hair!
Of course, if you can't get OEM reeds easily or you can get carbon fibre ones cheaply, then nothing overtly wrong with them... just don't expect to see or feel noticeable gains.
The OEM reeds should be replaced to the service schedule though. I'm not sure when that is, but I'm sure it's in the Service Manual.
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Andy.
NSR-WORLD.COM
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