i'd go with giac....and the vent you should be able to find from an auto dismantler for pretty cheap...i believe every a4 from 96-01 had the exact same vents, so they should be pretty common...

 

naw man get a turbotimer with a built in boost gauge and install it where the cupholders are

 

see with the turbo timers do they not mess with your immobaliser so you cant lock your doors when the engine is running.

 

US A4's have no immobiliser.
It does mess with the alarm and central locking system sometimes if you do not have it wired correctly. One possible problem is that you won't be able to lock your car while the car continues to run via the timer.

 

itll only run for like a min max