You mean the 911 Turbo? Porsche only claims 4.2 for that one.
They have the GT2 (Twin Turbo), which is 4.0.
This Ford beats both; its estimated 0-60 is 3.7 sec.
No, the 930 Turbo is what I meant. The Porsche 959 would definitely beat the GT if the 930 wouldn't.