I am going to get a .22 cal semi auto with the intent of adding a suppressor. My question is two fold...
1) which .22 autos come already threaded
2) out of these which ones are considered the best
You can always convert most existing .22's as well, but you'll need a gunsmith, or an aftermarket upper half (Tactical Innovations).
If you get a tilting barrel .22 then you'll probably want a can with a booster, otherwise fixed barrel designs like the Ruger Mk. III and Browning Buckmark don't require them.
The Sig is notorious for liking the high dollar high velocity ammo, my P22 does phenomenal with a can and subsonic ammo..... If you want to put a can on and run a damn near silent gun for cheap (relativley speaking, of course) the P22 is the way to go.
I don't have the threaded part for my P22, but I've seen them. I was thinking about getting it and the flash suppressor just because it looks cool. You should check out the Walther forum on the the Rimfire Central site. There are lots of good suggestion and tips for the P22.