Test: Box sit, Good Morning, and Deadlift set up
Mwod: PNF your posterior extensors for 2-3 minutes a side, or until you stop making changes.
Re-Test: Dead lift, squat
Bonus: Touch base with the Psoas Bias Extensor Stretch 2min each side.
Remember: With new range comes new responsibility.

http://www.mobilitywod.com/2010/09/episode-11-how-to-stretch-your-back-bits/