[Adrian E]

I was going to quote Van Aaken as an example as their offices were directly below mine when they were based in Crowthorne! They did a lot of work on diesel optimisation and seemed to take their time getting jobs right in the main.

I would query the benefits/risks of any tuning box that didn't involve some sort of data logging to check you're not getting near the limits on temperatures etc, diesel or petrol.

You can argue the toss for and against all day long but it always pays to bare in mind that your existing ECU is NEVER fine-tuned to your car, which is why they're so conservative as one size has to fit all.

In terms of warranty - if your car is still covered by an Audi warranty I wouldn't risk it. It seems the latest cars have enough sensing technology in them to know whether components have been stressed beyond factory limits, irrespective or whether they can find evidence of prior or current tuning. Audi will reject a warranty claim and black list the car for future claims, even after its sold on, which is worth noting if you're thinking in terms of avoiding a buyer thinking a car hasn't been remapped.