I've got a few K-Line MP-15 engines, and they run great! However the volume of the horns is way too soft. When I add around 10 cars or so, it's difficult to hear the horn at all. Short of replacing the horn with a different brand, is there a way to get more power to it? The sound reminds me of a battery-operated bicycle horn I used to have as a 5-year-old, only with a much lower volume.
Improving the speaker and baffle will typically help, but it's hard to say what you can do without seeing the specific installation.
I have some advice, but first I must ask: Are you good with electronics? One would be able to make a volume amplifier that is hooked in parallel with the track, and a potentiometer to help regulate volume. It would take a little designing, but if you're good with tech and willing to take some advice, just send me the specifications about voltage and dimensions. (I have two K-line MP-15's, NYC and UP, so I'll have a visual aid to help you by)
I don't have much experience with electronics. I've used a soldering iron a few times, but that's about it.