I added some things to my standard threaded barrel Victory, namely the TK trigger, Thunder Hammer and the DIP ventilated rib pic rail.
First, I really, REALLY like the DIP rail.
Link You put the OEM rear sight on this rail so that you have options of iron sights or other optics like red dots and pistol scopes. I normally keep a red dot on my Victory since most range trips involve at least some ringing of steel at 50 yards but it's nice to be able to switch to iron sights when I'm struck with that fancy. The optics return-to-zero very well with little to no adjustment as long as you put them back in the same rail slot. Note that this rail won't work with the Performance Center model. DIP will also change the front fiber optic pipe from green to red at your request.
I installed the TK Victory trigger first and the Thunder Hammer later. If I had it to do over again I would have done the hammer first. The hammer improved the overall feel of the TK trigger enough that I think that's all that might be needed considering how good the OEM Victory trigger felt out of the box. The feel of the trigger reset was especially improved with the hammer.
I originally thought that an aftermarket barrel would be in my future but after shooting groups from a rest using the OEM barrel I decided that any improvements in accuracy would be minimal at best. The DIP ventilated rib rail added enough bling for my rather unsophisticated tastes. Here's a pic, I don't use the muzzle device anymore as it didn't really improve the shooting experience.