Here is a post that helped me a while ago..
It's been a while since I posted this, so I'm sure everyone has missed it's presence.
Just to save you a bit of time ploughing through the search engines I've put my choice of top/recognised tuners for Audi's (VAG), and although originally was aimed at chip tuning encompasses general tuning as well, and does have a focus on the UK market;
Most recognised within the UK:
APR -
www.goapr.co.uk/dealer/index.html - Good maps and well respected, especially in the US. Just released OBD* tuning. Switchable options using cruise control.
REVO-
www.revotechnik.com/uk/ukrevo.html - Good maps, one of the first tuners to offer OBD* tuning in UK. Switchable options using switch (Dongle).
AmD -
www.auto-amd.com - More than just a chip tuner, they are a complete tuner unlike many others. Respect. New one-click system offers another option on tuning, by use of the OBD port.
Jabbasport -
www.jabbasport.com/Audi/Jabbachips/Contact/contact.html - For those that want to take their tuning that little bit further. Well respected.
Star Peformance -
www.starperformance.co.uk - Top mark tuning house, well rated by those North of the Border.
Forge Motorsport -
www.forgemotorsport.co.uk - No chip tuning of their own but they do offer a number of great tuning products for VAG cars.
* - OBD = On Board Diagnostic. Tuning which is done via the diagnostic serial port located on the vehicle, so no chip replacement is required.
European VAG tuners:
Oettinger -
www.oettinger.de or
www.roadandsport.co.uk (UK dealer) - One of the longest running tuners for Audi's. A great tuner with a great range of products.
ABT-
www.abtsportsline.co.uk/location.php3 - Again a long running tuner with good products. Official Audi chip tuning for The Netherlands, Germany and Belgium amongst other countries.
MTM-
www.mtm-online.de or
www.qstuning.com (UK dealer) - Well known for good maps with solid performance.
Projectzwo-
www.projektzwo.de or
www.roadandsport.co.uk (UK dealer) - Again a long runing tuner that's well respected.
SKN-
www.skn-tuning.com or contact SKN (UK) Ltd. on
www.scottsmototune.co.uk - Not so well known but good products nonetheless.
Upsolute -
www.upsolute.com - Austrian tuner, well known worldwide.
Other recognised tuners for chips mainly;
Superchips -
www.superchips.co.uk - Regarded as a general tuner offering nothing special, but map on 1.8T does produce good results!
Wetterauer -
www.wetterauer.de - Not so well known german tuner, but still heard of. Used in both the US and Europe.
DBM -
www.dbmengineering.nl - Similar to Jabbasport but in Holland. Nice product range with carbon air boxes. Produced a 420bhp S3 for the road!!
Bullpower -
www.bullpower.nl - Very little known about this tuner, but show good figures.
Sportec-
www.sportec.ch (Even though covered by AmD) - Relatively new to the UK scene. Good torque figures produced with the maps and satisfied customers.
Powerchips-
www.powerchipgroup.com - Hardly ever mentioned on the forums, like Superchips, but look to provide good results. The website is extremely good, and the detailed datasheets provided within minutes of an enquiry are full of info. Available through
www.mongooseexhausts.com or
www.motorsportworld.co.uk
All have their merits, and really it's a personal choice, and you have to check around before choosing in my opinion. There are many other smaller tuners who offer chips etc. but are not widely recognised, but can offer options cheaper than above, so additonal research will pay off.
Do not think for one moment that the above is comprehensive, it is only my opinion and based on my knowledge of tuning, the products offered and comments I have picked up on my travels and is intended to be unbiased, but I do have a weak spot for Oettinger these days.