A improved cylinder (IC) is just one step more open than a light mod (LM) Since a LM is pretty much right in the middle of the choke spectrum, to see much difference you should try either a open choke (cylinder) or a tight choke (IM or full) As I don't shoot 3 gun I can't advise as to which choke is best. The standard range of chokes from open to tight is: Cylinder, Skeet, Improved Cylinder, Light Mod, Mod, Improved Mod & Full. If I had to choose just one choke for everything I shoot it would probably be a Light Mod.
Charlie