So I installed this 2013 Silverado Mod.
I put it over FBI, which is the spot it's intended for, and I also put in the ELS file. I modified the textures for the vehicle so it can only be unmarked, and then when I tested it, the sirens don't work. The lights work perfectly well, and the sirens work for every other vehicle I use. This vehicle's sirens just don't work, though.