I just need to try and clear this up because I'm confusing myself. Those of you that have colored your guages and hvac, is it possible to just sand/paint the overlay itself.. or do I have to put in LEDs as well for it to work? It seems it would work fine without LEDs but, the threads I've seen include the lighting replacement

 

They just did that for more light output. I don't see a reason why you would have to do the led's. Your gauges and other painted controls may not be AS bright but you should still be able to see them fine.