If we’d departed on our long high-altitude X-C in our Cessna Cardinal prior to your “catch” of our misbehaving #2 top spark plug, our trip over the Rockies could have been a real nail-biter. Your analysis resulted in our replacing all the spark plugs prior to departure, resulting in our Cardinal running like a Swiss watch for the 39.0 hour round-trip. The peace of mind your service provided as “priceless.”