If you want to have a go at at real brutal squat program have a look here:
http://www.exrx.net/WeightTraining/RussianSquatProgramGenerator.html

Russian Squat Review 
My total for Russian squat  program was 140kgs. Not quite up to a Double Bodyweight Squat but real damn close.
End at of the Russian Squat Program 140kgs Start at 120kgs. Gain of 20 kgs in around 6 weeks.
And I got through it injury free.
Go here to check out more about the program and how I shaped up using it.
http://www.how-to-bodybuilding.com/russian-squat-program-report.html