The best 60 I ever got in my '07 with open diff was 2.227 due to wheel spin.

The best max speed was 113.19mph though so it really picked up its skirts once it found grip.

 

Not sure what the issue was , you should of been way better than 2.2, maybe your suspension setup, bad alignment? Just guessing. Because without tune I could easily be at 2.0 or just under 2 , with the tune as good as 1.88 but mostly I'm at around 1.92 mark now with open differential.

 

Even with the e-diff, the best I have seen in my '10 XKR was 1.891.

I would like to blame the track preparation but it could just be the driver