Street tires are good for 2.2 60's at the track. So if your not that low yet you still have room for improvement. I think my best 60' so far was 2.37 or something shitty like that. Try lower tire pressure to 25psi, that seems to help mine alot. Also some people like to preload to the drivetrain at the line. Pull up the ebrake, rev the car and let out on the clutch just till it starts to grab a little but not enough to move the car. Then when the light turns green let the ebrake down and finish slipping the clutch out. I have only tried this a few times but it may help you keep wheel spin down as there wont be such a harsh engagment off the line breaking the tires loose.