Has anyone had this done before on the 2.2 CDTi, and if so what were the pro/con sides of it? I've read that it can increase performance and fuel efficiency... but there seems to be very little in the way of downsides that I have read about... So I'd like to get a decent for/against view of it. Cost wise, it's less than £200... so even if it gets me an extra 2-3mpg it will take quite a while to recoup the outlay... But I do plan on owning this car for at least another 3yrs; and I do plan on some extra mods on top of those already done.