Just what i was gonna say about gear change speed.
As for instance i've done 4x 11.1 @ 123 - 124 mph, on my dog box.
but i have also done a 11.2 with a complete miss gear, with out it i might of done a 11.0 or better, but it onle lost me 0.1-0.2 seconds due to i was still moveing whist playing silly buggers.
i would guess, if Your car was fitted with my box on that run, i think you would of gained 3mph and 0.2 a second on the quarter.