Grand Touring Category - Purpose-built, highly modified silhouettes of series-produced sport sedans. GT cars are permitted tube-frame chassis with performance being equalized by allowing cars with smaller engines to compete at a lighter weight. GT1 through GT5 cars get progressively lighter and less powerful (GT2 - 300 to 350 bhp, GT3 - 225 to 275 bhp, GT4 - 200 to 225 bhp, and GT5 150 to 175 bhp).