I wanted to preserve a more moody atmosphere in the game vs the effect that stadium lights would provide so decided to try adding a few well placed spots. I'm very happy with how it turned out, highlights the figures and PF really well and still "feels right" and preserves the "Fear of Dark" mode where things get dark.
This is going get a bit long but in the interest of completeness...
To start with I had previously replaced all the factory white and red GI lighting with either WW (under the yellow plastics) or Comet 2 SMD Sunlight bulbs (under the slings and ball guides and other blue plastics), except I left the factory red bulbs in the very back of the pf since they didn't really interfere with PF art you could see anyway. I also put a red bulb under the plastic in the back right corner and disconnected the white bulb under left rear plastic (leaving the factory red bulbs) to provide a darker lighting in the lower back corners that don't need much light and to improve atmosphere.
I added additional spots to the right slight shot (2 headed), a single spot next to the pops, and another single spot near the top right flipper.
Since I'd heard that the node boards in Spike games can't handle a lot of additional load I decided to add one spot to each GI circuit (as you test in Diagnostics) to spread the load around. I have no idea if the separate circuits actually use separate node boards or all supported by the same one, but seemed like a good idea at the time. Maybe someone more knowledgable can comment.
Here's how it looks with everything added.
I used two spots on the right sling, one pointing between the slings and the other up the centre of the playfield. I kept the reflectors on these to prevent the bulbs from being visible to the player.
I used the Comet Op-Max WW bulb for the mid playfield (these bulbs are really impressive) and a Coment 5 SMD insane bright WW one for between the slings. I couldn't use the Op-Max bulb for between the slings as it sticks out past the reflector and was visible to the player. The insane bright bulb has no cover and is invisible to the player.
One spot over the upper right flipper to light the middle right side of the playfield. This one I left the reflector off since the player can't really see the bulb directly and it is less noticeable without the reflector on it. I used a Comet Op-Max WW bulb here and removed the largish cover it comes with using pliers since the cover made it visible to the player and without the cover it is not. It is amazing how much light this one bulb throws over the PF when mounted a little higher as it is. Also has no impact on visibility of the upper right flipper shot, other than providing a great amount of light.
These sockets are connected to the factory bulb sockets on separate GI circuits as shown below:
Finally the left side socket lights the pop PF area and the Madness Eddie figure. Again no reflector and using an Op-Max bulb with the cover removed.
The light is perfect as it leave the area immediately around the ORB a little darker so when that flasher goes off it lights up the PF in that area. Awesome!
I also used the Comet Matrix wire connectors to wire everything which come in handy sizes. Everything you need to do this can be purchased from Comet for probably less than $25 (sockets, bulbs, Matrix wires, and hex posts). Far more cost-effective and I think a better result than using Pinstadiums.