I have never heard until this instant of a gearhead who wanted to remove a tach from a car. I guess there's one in every crowd!
I vote for red belts or possibly blue for a slightly more sophisticated look. I really like all-black interiors but you need a little contrast.

As for tachs, I'm with Cab. Industrial design says needles are much more readable in active situations. Another thing learned from that source is to clock your gauges so the desired value has the needle pointing straight up.

R.