While looking at your web page it occurred to me that I owe the company my appreciation for avoiding a disaster in my 421C.

Some years ago I put dual JPI slimline tach and MP gauges at the bottom of my panel.  Though I have had some issues getting them to operate consistently, I have always used them as a check against my principal flight instruments.

The 421 was based for years at San Carlos (KSQL), an airport too short for a balanced field takeoff, even on cool days.

On a takeoff run, just before rotation, one of my mechanical tachs died; a nasty event even in flight.  One glance at the JPI tach for that engine convinced me that nothing other than gauge failure had occurred and I simply kept going.  The alternative would have been cut power and brakes, which would have put me through the chain link fence at the end of the runway.

As a backup, your instruments saved me a very large repair bill, and perhaps the airplane.

John B.