The Friday night street legal shoot out we participate in to do these 1/4 mile passes at mission raceway does NOT allow open headers or un muffled cars. It's a street car shootout where it's always heads up and people are just racing their cars and having fun. You can get 9 or 10 passes in while they are open because it's not a bracket race, just heads up to get people off the street and into a track where they can go all out safely.