Hi,
I run a C-6 behind a milder 460, still get 16 mpg on hwy with two carbs.
1- not many transmissions will handle 600 hp and torque,a C-6 will.
2- gas mileage has more to do with how much overlap your cam has and how fast you like to drive, the C-6 has a little loss comparred to a standard trans, but not as much as a wild cam.
3- a good prepped C-6 is 3 tenths quicker in the 1/4 than any standard trans, just look at the NHRA super stock records,of course a lenco is faster but not streetable.
Good luck,
Perry.
