The Bilsteins will be an improvement. Actually, a solid steel rod would be an improvement over the AVOs. Save your coin and buy some single or dual adjustable QA1's and you will be amazed how improved your ride becomes. Getting the correct spring rate is also very critical. Some like 350# while others swear by 400#. All depends on how responsive you want the suspension to be.
With the rear shocks out, you should also upgrade to the seriously improved upper shock tower brackets sold at Cobra Valley. If you have never serviced the factory brackets or the bolts, you are dancing with the devil.
Cobra Valley's SUPERFORMANCE Rear Suspension Mount UPGRADE