I had the pleasure of taking the previous owner of my Alfa Romeo 4C around Road Atlanta for a session with Jzilla Track Days. Ran a respectable 1:43, 3 laps in a row. 
This is primarily my street car and I had a passenger, so I wasn't jumping curbs and super late braking. With some better tires, more send, and cooler temps...1:39 should be pretty achievable.

Stage 2 tune
Lowering Springs
Exhaust/downpipe
Endless CCRG front brake pads, Tarox Corsa rear
Continental Extreme Contact Sport 02 tires, 225/255