Personally, I don't like BTTF pinball. I have a friend who has one ONLY because he's the biggest BTTF nerd I've ever met. He does not like pinball. He only purchased it for the theme. I've played it several times, and I've tried to like it, but it's not happening.
Data East missed a huge opportunity to make it great. They could have added a going back to '55 challenge or 2015, or a beat Biff challenge. Nothing.
The one thing I do like about it, is that is says DELOREAN on the back wall and there's a DeLorean millions challenge, but that's it.
As far as modding one, all you could do is improve it, because it needs it in a bad way.
Not trying to stir things up, just wanted to answer (and add my opinion). Definitely mod that thing!!!!