What is T1 in motor racing?

In SCCA (Sports Car Club of America) amateur road racing, T1 stands for "Touring 1", which is a class of V-8 and V-10 cars like Chevy corvettes and Dodge Vipers. T1 rules restrict race preparation to the point where, other than safety equipment (e.g., roll cages, harness, fire suppression systems) the cars are largely in stock configuration.