So I was playing Engineer with the (as you already know) overpowered Short Circuit. I realized how epic I was and wanted to make the experience more.. magical. Anyone know how to change the sound the Short Circuit makes? (Using the "custom" folder in the Steam\steamapps\common\Team Fortress 2\tf directory.) If someone does actually have an answer, you can refer to the sound I want to use as "airhorn.mp3". Thanks.
The custom sound needs to be in a specific format (WAVE/16bit/44100 Hz/Mono), which requires that you convert it from mp3 (you can do this with
Audacity). It then needs to be placed in the right folder with the proper file name. So in this case the file would need to be "C:\Program Files (x86)\Steam\steamapps\common\Team Fortress 2\tf\custom\[Any Folder Name]\sound\weapons\barret_arm_zap.wav" where [Any Folder Name] can be anything (even "[Any Folder Name]").
If that sounds too complicated, just download
http://calciumgaming.net/dl/sxh/ShortCircuitAirhorn.zip and extract the "tf" folder in the zip to "Steam\steamapps\common\Team Fortress 2\" for some MLG airhorn fun.