First off, using the same ratio's for each car will give different results, the cars aerodynamics are different and the weight, the dimensions of the cars are different also. The racing Viper the GTS-R has aerobody parts which generate downforce, downforce is when the wind or air hits the car and pushes it down so it sticks to the road and generates grip but it reduces speed so if you have two identical cars but give one more downforce generally the one with more downforce won't have as fast a top speed but it will corner better (remeber this is only on a general basis) to get the GTS-R to hit the same speeds you need different ratio's but don't ask me what they are, what you will find though if you give each car the same settings and same tyres front and back the GTS-R should whip the GTS's proverbial on any circuit that isn't just left turns, the GTS-R is faster than the GTS even when it doesn't have as high a top speed.