Read the Recipes section for most of the basics ...
http://www.gnttype.org/techarea/recipes/recipepage.html
As stated ... it's about more fuel/air and a chip calibrated to take advantage of that.
With good gas, some traction, a basically stock car (with air intake, fuel pump, test pipe, sticky tires) should be able to run solid 12s with sixty foots in the 1.6-1.7 range and trap speeds around 107-109 MPH.
This would require 100+ octane gas and 20 psi boost (and tuning).