BiTurbo:

This 959 S with all the gizmos and dual shock absorbers per wheel weighs 1,350 kg, yet Porsche couldn't deliver a 911 R that could weigh under 1,300 kg in 2wd form without  turbochargers and intercooler piping angry

To be honest, I haven't weighed my 959S but I'd say it's closer to 1500 kg than 1350 kg. And that's fine, considering the power and it's delivery 1500 kg is not too bad.