Orlando, thanks for providing the pictures of your install. Really clean and really nicely done. It looked like the step lights were originally wired to track power, which is why I asked how you did it. I almost always renumber my locomotives so I don't worry about the numberboard lights. I do like how they redesigned their ditchlight lighting.....far better than the first run of ET44's. I removed the factory lighting from my ET44 and replaced with nano LEDs.
The placement of the speaker housing is much better in the Dash 9 than in the ET44. On the Tier 4 I felt it was too far to the rear and it was noticeable when the locomotive went by. The Dash 9 speaker housing is right below the exhaust stack, which is perfect. I should have a couple of speakers sitting around that are the right size, so I'll give those a shot. My other thought was to try and shoehorn one of these in there by cutting it down and placing it diagonal:
http://www.tb-speaker.com/products/t0-2008s. I'd have to remove a huge chunk of the weight though. Lots of bass on that speaker, but not a lot of volume.
Excellent video BTW. The sound is great, especially the volume of the horn. That's what drives me nuts about so many DCC sound decoders....you can't even tell the horn is playing. Kills the immersion.
-Kevin