Here is one suggestion.
http://www.soundtraxx.com/documents/appnotes/SW1000&SW-1500App.pdf
SoundTraxx has a new generation Econami decoder but no idea on how to install it. The Tsunami design is at least ten years old.
Some like LokSound better than SoundTraxx. TCS Wow is another fairly new sound decoder.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Link to Soundtraxx install. If you don't want to modify frame, take out the cab interior and put speaker in there. Joe