I use Dr Beasleys matte car care kit (Bear Wax Factory £94) on my stealth grey raider,Angelwax on the same site do matte car poducts(there other products are very good).Another good product is from Nanolex at Polishedbliss for about £84 per kit.If price is a issue Autoglym detailers use their own bodywork shampoo and sealant as per their website on Audi and Bentley cars (have used these products when I first got the car).You can use a ph neutral snow foam such as Angelwax or Carbon Collective.Hope this helps Simon.