Update on the Terraclean process-
Had the service done today and have to say that first impressions are very good.
Driving to the garage was a steady 60 mph returning 42.4 mpg.
Car taken into bay and plumbed in to the machine.
Mechanic bypassed the fuel filter and ran diesel directly to the machine (on petrol cars the machine uses it's own fluid) and then to the injectors (the machine has it's own fuel filter).
Machine powered from the car battery and started up with the revs set at 1500rpm
45 minutes later the machine stops and they reconnect the fuel lines (that's where the fun started, 20 minutes priming the fuel lines to get the beggar to start again.
Apparently on diesels the system uses a fuel additive and a ammonia type mix to decarbonise the system.
Trip back home at same speed on same road returned 49.9 mpg and around town where I'm usually set at 33.4 mpg I was getting 39.6 mpg.
Suffice to say, there is already a noticeable improvement in fuel consumption and, allowing for the placebo effect, I could feel that the engine was running smoother, quieter and moving through the revs better.
Acceleration seems smoother and even allowing for my Bluefin remap felt more powerful.
I'll do a more thorough run about on various road types and driving styles over the next few days and then I can be sure that there are real gains.
According to the mechanics I had a yarn with, they have all done the TerraClean on their cars and in a couple of cases not told their other half's and even they noticed something was different.
Pity I already had a Bluefin done as they were offering a package of the Terraclean and a Quantum Tuning remap for £250 (bargain methinks).