Hoping for 13.99...

[91LX2Bfast]

Do you have a manual or auto?
Your mph seems low, so I am going to guess you have an auto. But, even with that, it still seems low. Did you run going into a headwind, or are you at a high elevation? What were your 60ft times? Can you tell us about how you drove/shifted?
The cold air kit really isn't going to make much of a difference, and I would assume the pulleys to drop about .1- .15 sec. If you have an auto, throw in some 4:10's and a chip from www.customchip.com, and you'll go easy 13's.
If you have a 5spd, why was your mph so low the first time you ran? In good conditions, a 5spd car with pulleys, H-pipe, K&N, and flows should go 13's. It'll all depend on driving and traction. There are a number of stock '99+ GT 5spd's going consistant high 13's bone stock.
Again, a set of gears would go a long way to making consistant 13 sec passes a reality.