Auto or manual? Street tires I assume, or are you running drag radials or slicks? I'll assume some stuff just to answer your question.
The best I found with my 01 GT on launching is to feather the clutch and hammer it when I know I have traction. Dumping the clutch on street tires is a bad idea....
You will want to shift a little later from 1-2, and then a little earlier 2-3 and 3-4. My powerband is a bit higher than yours but the best run I've had (in my sig) I shifter about 5700 from 1-2, then about 5500 2-3, ended at the top of 3rd (5900-6000)with the stock 3.27s.
You def have a faster car than a 16.1, you should be in the mid to high 14s...work on your 60ft times and that will bring down our 1/4 mile time.
Launching on 4.10s will be a lot tougher due to the increae torque multiplication, but same principal applies.
Also, if you can afford it, you need to do a PI Intake/Heads/Cams swap, or, at a minimum, a PI Intake...the PI Intake will allow your engine to breathe above 4500RPM and will give a solid 15rwhp gain up top.
Again, give us more details on tires and tranny and I'll try to help a bit more....
Matthew 26:52-54 / Go Pack Go!
1987 Mustang GT Hatchback - 2V Mod Swap In The Works
1997 Lincoln Town Car, PI Intake/Cams, Sofa-On-Wheels, "Fat Tony" we call it
2001 GT Convertible - D1SC / Geared / Cammed / 440wh 400wt - TOTALED 2/2019