OK, so I've just been and picked up an 'E' marked baffle kit to retro-fit my existing 'competition only' can......
First impressions is that the loud "BAB-BAB-BAB-BAB!" has turned into a "chuff-chuff-chuff-chuff"......... if you know what i mean, so I reckon it is quiet enough to keep PC Plod off my back..... though I'm still not 100% pleased. The backfires are not as agressive, more a sneeze now than a bang.
I have a lad looking into the correct 'E' marked silencer for me, so fingers crossed! I'll be amased if it is here by Wednesday though, as I'm off to Italy/Slovenia with the advrider.com crew for a weeks worth of trails.
When I get back, I'm going to look again at this set-up, and make some changes.

Timpo.