If your car is modified, a boost gauge is essential to monitoring your turbo system and how it's running. Gauges are cheap, neat looking and easy to install, so why not?
Some notes about gauges:
-Choose between PSI and bar. MOST gauges read PSI but some out there read bar, PSI seems to be a more common measurement. 1 bar = 14.7 PSI.
-Choose between 52mm and 60mm, depending on how you intend to mount the gauge.
-Defi BF gauges, which are very nice gauges, require a controller to make them work. This controller is about $110, but the gauges WILL NOT work without it.
-There are many brands of gauges that are used. Defis are regarded as being among the highest quality gauges out there. Other brands that are used include: Autometer, ProSport, Stewart Warner, VDO and Revo, just to name a few.
As for mounting, there are very few spots to mount gauges inside the TT. Here are several typical solutions:
OSIR Mantis gauge pod, replaces ashtray and costs a jaw-dropping $300 (no gauges included!)
You can also use an A-pillar mount from a Toyota Supra...TTstuff has them:
Finally, one of the most popular gauge solutions is the vent-mount gauge:
A 60mm gauge will fill the entire vent hole (meaning you can't get any airflow around it anymore) whereas a 52mm will leave some space, meaning you can retain vent functionality. The pictured gauge is 52mm. Most gauges can be mounted with their included hardware in the vent, however if you can't get yours mounted up right, Modshack sells a ring insert to mount your gauge. Personally, I've used this vent ring on both my gauge installs because I'm a perfectionist and HAVE to have the gauge right in the center.
There are several writeups on installing boost gauges; generally it's pretty simple. I believe the AudiWorld FAQ has a link to one (see my first post).
What boost gauge do I run? A Revo Rev2 with an OEM needle modded into it. Perfect match IMO: