Although Terraclean is a fairly recent process it does indeed sound like a God send, black smoke & rough idling gone & it drives smoother. How much better does it get? I believe BuckMr2 has a high opinion of Terraclean as well.
All for £80.00 Inc. VAT.
Lots of people experience black smoke Etc. Sometimes cleared by using Millers or other fuel additives, but if that doesn't do it then this sounds like the nuclear option. Very interesting Post, thanks for the recommendation.