Okay :) 

In that case what sort of strength would fit a bit better? I was thinking that at Level Three [i]all of her hair[/i] could hold the same amount as 1 millimeter of Dyneema Fiber can withstand (240kgs/529lbs), and then doubling that at Level Five (480kg/1058lbs). This would be because her hair would act as an incredibly strong fiber, keeping with the Hair Manipulation theme.

This would also only represent what her hair could [i]hold[/i] not [i]lift[/i], meaning that she could catch something and lower it to safety, but not just pick up and hurl traffic willy-nilly. I would regulate her hair to only being able to lift her body weight (140lbs) at Level Three, where it would stay and not increase at later levels.