I added post lights - i didnt want the lights to effect the line of sight of the ball on the playfield, so they are installed/floating on the bowman's plastic - its a very cool effect and lights up the centre of the playing field nicely.
I also swapped out all the warm leds for comet's sunlight leds: http://www.cometpinball.com/SearchResults.asp?Search=sunlight. These really make the playfield colors pop, Id recommend it to everyone.