this may seem crazy but i did this and it worked. u can average out cars ger ratios so the car u r tuning will be faster. trust me i did it on my MB CLK GTR. its stock mhp is around 240 if your lucky. i averaged the cadilac cien, mb clk gtr, and jag xk320 and applied the new gear ratios to mb. the top speed was 253 mph.
NOTE when averaging gears divide one # up (3 cars then divide by 4) or else u will get all your gears at the max
NOTE when averaging gears divide one # up (3 cars then divide by 4) or else u will get all your gears at the max