I just got 345 x 5 for my first time yesterday, and I don't feel as if I stalled out yet. I can probably continue to add 5 lbs. per week for another few workouts until I'm maybe up to 375 or so. But DAMN, 345 felt pretty damn heavy to me.
But how the hell do you crazy SOB's manage to deadlift up over 600 lbs. and stuff?? Actually I know how you do it. You train your ass off until you do it, but I'm just saying that 600+ lbs. is insane. 600+ lb. squat.... yup that's also insane.
My PR's right now are:
Squat - 255 x 5
Deadlift - 345 x 5
Bench - 217 x 5
I don't know what my 1RM's are though. It definately feels heavy to me now though, lol.