All I have is rockers and the smallest turbo kit (S256) out there for a GP and I have run 13.01 and have a best trap of 115.56 on street tires and traction being a serious issue with much more room to grow. I also walk my buddy's mid 12's LS1 hard on any roll. 12's on the track might not be mind blowing, but trapping in the teens on the street puts down most cars I have run into.
A family car in the 12's is pretty quick.