I remember seeing a similar mod in an Evo somewhere - possibly Kevin A's car ?
I've thought about it myself, since I want somewhere to mount oil pressue and amp; temp gauges (the alternative is in the din slot under the ICE head unit, but that's a little out of the eyeline - and I may have another plan for that )
Have a word with Justin for somewhere to mount your gauges. He has a decent A-pillar pod that replaces the whole A-pillar trim but matches closely the existing plastic pattern. I got one and it looks great, not fitted yet as I am waiting on a pressure gauge but even so I reckon its the best one out there.
Have a look here for a picture or go to his website http://www.torqueic.com
The guy that fitted his gauge in the vent was Geoffers, and he
did a really neat job. But it is something you can easily make at home
(Geoffers did, he bought the boost gauge from me), just cut a piece of
plastic to size and cover in carbon fibre film
If you dont want the A-pillar pods,HKS now sell a single din guage panel for
the evo which sits under the stereo and holds 3 x 46mm gauges and is only
£28.50|PLS|vat, or they do a gorgeous console panel which replaces the passenger