Originally Posted by seanblee
It reads like Terraclean hooks up to the fuel system, so that won't help with this particular problem on a direct injection engine (given the whole cause of the problem is that the fuel goes straight into the cylinder so doesn't wash the back of the valves).
Terraclean also have a system as well as the one featured on Wheeler Dealers specifically for cleaning inlet valves on direct injection engines. http://www.terraclean.net/product.php?id=2
I do not know if it is widely available in the UK yet. Might be worth a try, it will certainly be cheaper.