neat boost gauge
 

http://www.machv.com/headupdisboo.html

Pluses:

- no hoses, only wires through the firewall
- no need to mount a gauge in an unaccommodating dash

Minuses:

- I'm a psi guy, no hablo bar. Time to learn?
- do I trust the engine to shut off?
- $260!

Sixto
91 300SE
81 300SD

Sounds cool, but I don't know how the turbo timer system would work on a diesel. On gas cars, they keep the ignition circuit alive after you take the key out. Our cars have vacuum shutoff, so you'd need a pretty good imagination to get that one to work. :)