believe what you may, thats cool... all I know was what I saw/heard/felt, so yeah... the porsche driver meant he couldn't race any faster than 70, not that he couldn't at all... and yes the ZO6 was definately going hard on the gas, he told me he was, and two car lengths from 70-105 is like 3 seconds, so thats quite a big difference...
as for cruising in 6th at 60... I normally do that to save gas, and when the is300 tried to race I was too lazy to shift, so I just floored it, even though 6th has a below-1 ratio
