Rabbit,
I would recommend you go toAutobahn and pick up a Trust/Greddy turbo timer on special for $99 (usually $149) - I have had to of these turbo timers and they are great. Check out the link below to learn more about them:
Greddy Turbo Timer - Website
Some of the main features that I like consist of - Digital Speed Display, 0-100 times, Timer, Countdown Timer, Racing timer, Max Speed Display, Voltage Current Display - Also has an Automatic timing function that determines how long your car needs to run down for before it will turn off.
I can install this for you if you want - Save you having to pay somone. Just wacked one into my R34 on the weekend - Very simple job.
Last time i installed one into an r33 was my one (before I sold it)...probably around 1 year ago....
As far as a boost gauge go's, we could try and find somewhere to mount it, R33Cruiser and I usually find some neat places to mount gauges. If stealth mounting is something your after, we are more then capable of helping ya out with this
Hope the above helps. - I'd seriously look at getting that Turbo Timer whilst its on special (go to Autobahn Kawana and ask for "Cameron" or "James" and tell them Christian sent you in to get one of the Trust turbo timers while they are on sale. If there arent any left on the shelf, ask them to order you one in at the $99 price (if you have any problems, just let me know and i will ring them for you )
... No one can beat that price, well maybe Nengun - but then you pay for postage and its cost's more, and takes time to get here from japan.
Hit me back.....
Chris