This is a tough one, because to me "ricing" or "riced out" carries additional negative undertones (racism aside). I have always heard it used in a way implying that it was referencing enhancements done in a cheap or gaudy/classless way. Think of the most Razer-like LED adorned gaming PC setup, that could have easily been described as being "riced up".
I think the phrase "decked out" works OK, and seems to also lack the negative connotation, which may or not be in line with the goal here.
Also, seeing your example ideas you shot down, I am not sure you full understand "souping up" phrase. The term "souped up" has been in use for over a century and I still hear people use it pretty frequently. It is generally meant to imply something has been made faster or more powerful, frequently with cars, and probably why some people argue it is a shortened version of supercharged. I agree that it probably isn't a good fit here, but not being of how it sounds.