When I had 260rwkw I managed a 13.4 @ 107mph with a 2.1 60ft which was still not that good.
That was in my T with 5sp T5. So it's your 60ft that is letting you down, your mph would indicate a low 13 pass in a manual.
I suggest you drop your tyre pressures at the rear down to about 22-25psi. I suggested this to one of the XR8 ute guys last night at Calder and he went from a 14.6 and ran a 13.8.