OP

Quoted from markmon:

I suggest the connector at the coin door that connects the 12v LEDs in the coin inserts. It's a 4 prong connector with a yellow and black set of wires.

No, I disagree. The idea is to light the playfield so you can see the ball and play the game. Bright colored lights won't do it. The current GI, while dim, serves the purpose of awesome lightshow just fine. The addon is to make the game playable. Color changing or heavily colored lights (blue, green, red) will not help with game visibility or ball tracking.
The purples are very nice on this game. They do a nice job of making the playfield glow without making it look like over headlights are turned on. And they do it without looking purple or making it hard to track the ball. If you use whites, you'll see but the playfield won't glow and it will look like the overhead lights are turned on. You lose some of the magic you gain playing in the dark. On paper, purple sounds ridiculous. You have to see the installation to understand.