If you're looking for chokes, I have to recommend both the Primos Tightwad and the TruGlo Gobbler Stopper.

I haven't used these chokes in 20ga, but in 12ga, these made patterning at 40yrds a joke. I bought these two to try against eachother in my wife's Benelli Supernova, planning to buy another of the best one to use in my own Supernova. We tried them out with 9 different loads and at 40yrds, with EVERY load, we were getting 10 or more spine hits on turkey targets with nice even distributions and 40-45% of the shot falling inside a 10" circle... FOR EVERY LOAD WE PATTERNED!

With both chokes (the Truglo in my wife's Supernova, and the Tightwad in mine), we had to move out to 50 and 60yrds to really make a decision on which load to use.

The Gobbler Stopper is available as a combo with a snap on set of fiberoptic sights for the same price as the TruGlo. We actually upgraded both of our shotguns with TruGlo adjustable fiber optice vent rib sights ($40), which allowed us to "sight in" our shotguns to really dial in the groups.