As many readers may know, the water temperature gauge on a Mk 1 TT (as well as most other Audis I believe) displays not the actual temp of the coolant but is 'weighted' to display 90 deg C if the real temp is in the range 83 deg to 98 deg (or somewhere close to that range).
You can read the actual temp either through vcds or through the display on your HVAC head unit (or additionally through such clever devices as FIS Control which reads selected values from OBD II directly to your DIS display in the middle of your instrument cluster).
I read somewhere recently that the water temp gauge can be recoded to display the real temp (this makes sense as presumably the data from the sensor is manipulated in the ecu - so it can probably be un-manipulated). Unfortunately, there was no detail.
I did a search of this forum but found nothing directly related.
This question may be more appropriate on the Ross-Tech forum (where I'm heading next) but had anyone heard of this?