There are tactics to run a solid shop but that does not guarantee that you will be successful. I worked at and helped run an all z car shop for 10 years. We serviced all years of Z's and even took on all kinds of other cars just to keep busy. Even at that, half of our income came from parting out junked Z's. I have also seen multiple Z specialty shops come and go. It is not an easy market segment to be successful in. I love Z cars but most Z owners are cheap as hell and most of the Z cars out there are busted piles (with owners that are about the same). Like everyone else has said, good luck with your venture but I don't see it going well. Even the performance shops that specialize in expensive makes more often than not don't last too long.
