The Artist Tweaks are some of the small improvements that Paul has made to our instruments over the years. If you have a guitar built in 2008 or later, the Artist tweaks have pretty much been built into the guitar, but an older guitar can certainly be improved upon with the tweaks.
Unplated grooves in saddles or unplated stoptail bridge, unplated intonation screws, unplated tuner shafts and a couple other secret things I cannot divulge without getting on the wrong side of the big man.