New GTO quarter times

had a guy tell me his stock goat ran 13.1.
Is it possible? It was an '03 model.

Nope, not possible. There is no '03 GTO. The '04, however, I've seen in person running 13.40s. I suppose with a bit of tweaking and some tires, 13.10s isn't out of the realm of possibility.
I know there's some guys in SoCal turning high 10s with theirs, adding electronics and other bolt-ons.

the only gto that might have a prayer of running a 13.1 stock is the 05