Present setup, other than factory parts: Bell & Carlson Anschutz Target Stock, Titanium Extractor, I think every part of the trigger mechanism but the triggerguard/frame replaced with VQ or PC parts and polished/tweaked by competition gunsmith, GM 20" stainless fluted .920 barrel, hex takedown screw (for reliable torque setting), replaced a few springs, polished surfaces of bolt/receiver/etc.). Now that I think of it, I probably have $500 on top of the cost of the factory 10/22 into it, not just $500 total.
It still won't compete with real silhouette guns like the Anschutz, mainly because of the comparatively poor trigger design of the 10/22 and the very slow locktime with so many moving parts. For what I have in that gun, I could have gotten an excellent used Anschutz that is what the B&C stock was copied from. For a little more, I could have gotten a used model 1712 that would shoot circles around the 10/22 and would be an actual top-end platform for customization if I decided to get really serious with silhouette shooting later. To make a 10/22 really competitive in master class silhouette shooting, not a single part in the gun would be stock and you'd have to start with a Kidd trigger group (since the Kidd design is different from Ruger's) and all custom parts. When you were done, you'd still have a gun that cost at least as much as a custom bolt gun made from an Anschutz 54 match action and it wouldn't be as good for offhand shooting because of the slower lock time and more, heavier moving parts that move before the bullet is actually fired.