Bone stock: 13.9-14.5
GMPP/aftermarket tune and exhaust: 13.0-13.5s
12.9s is not well so documented because the driver is not using forums but I can guarantee you is real, DBG the owner of this forum can vouch for him, I met the guy while I was in US and saw his garage. His daily driver is Kappa too

his strip car is a blue Cobalt, full interior, stockish 11.4s IIRC

search this forum, DBG posted his timeslips
