For me it was when I saw this car Marsh Coupe at a hillclimb. It was black when I first saw it few years earlier around 1987 and ran 4 motorcycle carbs (mikuni's?). I was astounded at how quick it was - up till then I thought you needed a big engine to go fast. I also worked with guy at the time who'd had a very quick light blue 1200SSS who was forever on about how great these cars were.

Was then hooked - traded in my Mk3 Ford Cortina on a std B310 sedan, Worked the engine and raced it etc plus still used as daily driver. Rest is history.