I personally use a mate of mine Ian, http://www.iamotorsport.co.uk/ 07746888200
But as Ekona said DMS are very good aswell as Abbey so It depends how far you want to travel I suppose, where in kent are you?
Check these 2 threads out
viewtopic.php?f=93&t=42023
viewtopic.php?f=93&t=42422
i don't agree with it being a common colour, All I see are GM, Sunset and Azure's about the place.
Bloody silver & blues, should have got a Black one, well sought after
Unless you have excessive oil consumption I wouldn`t worry about it, besides it would likely to be coming though a weak/damaged piston ring rather than through the plenum so check the tips of the plugs if your really worried. Personally as previously mentioned I would go with a dodgey CAT or perhaps the left hand silencer has fewer baffles in than the right one