Unless your engine was built before 1975, as others have said, you're going to mess things up running leaded gas. And BTW, how meany MPG's did the cat delete cost ya?
My tri-hull is a 1970, and if I don't go to the airport and get some 110 low lead to mix with my pump gas, those valves chatter like the head is going to come off that old Iron Duke. One of these days, if I ever get money ahead enough, that old ID is going to get a more modern head, a new manifold and an throttle body carb. And then the points are going to take a trip overboard as well in favor on one of those Morosso electronic kits.