He wanted to go all-out and have sound. Space is VERY tight, but I made it work.
Circuit boards are removed. I have one to go here.
A plain decoder fits easily in the roof.
An ESU Nano v5 with the new board and shrink wrap removed just barely fit. I insulated the walls with Kapton tape. I wrapped the decoder with Kapton and superglued it to the roof.... socket exposed.
Here is the wiring harness. Left is the speaker mounted in the nose. Sitting on a custom board with traces cut for the speaker. Stock light board next and runs under speaker.
Nano board in the middle, stock headlight on right.
Since I lost weight when removing the nose weight, I added weight back in 3 spots. A squarish lead weight center, Tungsten putty on left....
And Tungsten cubes on the right.
Here's the whole assembly.