Tach Questions again

[vrona@ix.netcom.com (Steven Verona )]

I remember a thread from last year about the feasability of adding 
another Tachometer to an Audi 4kq.  The end result was that there are 
no aftermarket tachs that will work right out of the box.  I want to 
get a large tach for the race car and was wondering if a tach for a 4 
cylinder car might work.  I would think that it would return rpm 
readings about 25% higher than reality.  This would be fine as I could 
calibrate my mind;-)

What I am really trying to do is install a tach and/or a series of LEDs 
that will light at different rpm ranges.  I would put the LEDs in my 
helmet so I could de them out of the corner of my eye.  Something 
adjustable that would allow a light to come on when the rpm<4000, 
another between 4 and 5k, another between 5 and 6k, and another over 
6k... something like that. This would allow me to keep my eyes on the 
road and better judge my shift points.

ANy ideas?

Steve Verona