Bone stock E36 M3 on tired suspension, street tires: 2:02 approximately. I'd probably be faster now in the same car, but not by much.
C5 Z06 410whp, some suspension and braking mods, Hoosier scrubs, about 3,400lbs: 1:55.8 on first session of the morning, track still damp, vibration caused by bridge bolt coming out of caliper (!) and wheel stud about to break (!!). Probably at least 3 more seconds in that car with me driving but then proceeded to break the wheel stud so car was done for the weekend.
Fox body Mustang (!), supercharged, 240whp, live rear axle but suspension + braking mods, BFG R1 scrubs, around 3,200lbs: 1:56.3 (!) with 200lbs passenger and some revs still on the table (didn't want to break someone else's car!).
Stock 2001 C5 Z06, 340whp, stock everything except safety, probably around 3,300lbs, street tires: 1:56.2 (not me driving).