I drove a Porsche 914-6 (the 6 cylinder hot rod one) years ago. I had it modified with bigger cylinders, higher compression, high lift cams and so on. It was pretty fast.
One day, a Grand National pulled up along side me. I think he was at the next stoplight before I shifted into second gear. I was amazed at how quickly the distance between us grew. Since my car was a 13 second car, I'm 100% sure that GN was solidly in the 10's, and maybe even faster. Amazing car!