yeah...Nittos are pretty bad for the track..(better than street tires yes) but its hard to make them stick like say a MT or even BFG. i used to run the nittos at 16-18psi back when i was stock/headers only, cam only and the best i could get was a 2.05 60', no matter what i tried.
you're MPH should have you in the 13.1-13.3 range if you can 60 a little better. lower that to a 2.0 and you'll see low 13's all day long.
my suggestion would be to air down the tires a little more, say to 17-19 and launch the car at about 2800-3000. dont snap the clutch, ride it out and you should improove the 60'. it'll take some getting used to but its the best thing for these cars. anything lower in rpms will bog the car, anything higher will just spin them. your clutch will hate you for it but if its stock it wont last very long anyways so let er eat.
btw i still have a torque arm that can help your traction as well...
