Why so fast when cold?

Its basically because the colder and more dense air allows for the engine to be more efficient.
-But i recommend that you stop "enjoying" those first few minutes. When i still had the GT, i wouldn't go over 3k until it was atleast warmed up. The seals haven't had time to expand fully yet and the oil hasn't completely circulated everwhere. Just lay off of it until it warms up bro

Check this out; it's a description of setting options for the SCT chip:

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AF Ratio adjustment across the RPM range
Timing based on load / RPM +
Auto trans shift points, Line pressure adjustment
Rev / speed limiter
Speedo calibration for gear changes
Idle & 2 step rev limiter on certain manual trans mustangs
Open / Closed loop adjustment
O2 sensors
Maf / Injectors
EGR / boost bypass valve shut off
Hi speed fan temp on /off
And much more.

**

Based on this list, you could have the programmer set the car in a closed loop mode. Be nice if you could have closed loop mode on a switch.. wonder how that would run.

you are pulling more timing