Hey guys, I am also looking at going with 3.91s with a M6, would you suspect the extra 250 rpms at 80mph in 6th gear would affect the highway mpg much? I would think the lower gears would actually increase the mpg around town due to less strain on the motor, but I am concerned with the highway mpg because I drive the camaro long distances more frequently than around town.
Performance: Kooks LT, 3'' Exhaust, V-Max TB, Roto-Fab CAI, Custom Ported/Port Matched Heads and Intake
Suspension: BMR Adjustable LCA's, BMR Trailing Arms, Poly Bushings, BMR Toe Rods
Coming Soon (still in the box): Procharger F1R, G-Force Axles, 3:91 gears w/Eaton Truetrac