Have a few 10/22's, and the best upgrade is the titanium sear and hammer. Only problem is modifying to accomidate the safety. Ti is very very very hard to mill or cut down to fit your safety. I ruined stones, and a diamond stone to do it. The extended mag release is second. All these are high quality components.

Now you can easily be caught in a trap of upgrading these bad boys so be careful to watch your wallet and determine how much its worth to you.