5.6 twice so far is my best. Launching the car from 2000 rpm with t/c off. I live in Florida so pretty much sea level. Maybe with an empty tank I can get to 5.5. The only thing that I have to improve is the spinning which makes me think that in order to get to 5.1 sec I need stickier tires. Don't know if it makes sense, just sharing my experience.
