I don't know about 2011s, but there are a couple of guys over at BHSpringSolutions dot com who have put some thought into spring combinations and slide timing. You may want to go over there just for some ideas. They have videos, text, spring kits (for 1911s), etcs. As I understand things, you have to consider not just the recoil spring, but the main spring and firing pin spring, as well.