What are your best times on the various L4D survival mode maps? Here's my one for startes, 8+ minutes on Dead Air, with all four survivors staking out the roof of the rescue plane. A high reward but high risk scenario as smokers will get you in the end. There's at least two ways up onto the top of the plane, both using baggage trucks. One can be used as a stepping stone onto the nose, and another can be tipped on end to gain access to the right wing. The 8 minute time could be topped by a decent team, just need some top smoker snipers!