DISCLAIMER: Its been brought to my attention that some people are experiencing strange sound problems after installing the sirens. For instance tire sound more high pitch, or during a police chase with a 3 star wanted level the police helicopter pitch sounds strange. I am currently trying to trouble shoot and debug it. Though both sound files right now are in the correct format, Mono 16-bit, I suspect the length of the sound sequence maybe too large. I'll see what happens if I trim them down to the original sound files, which the siren will loose multiple tones, airhorn, yelps or pier. For reference for those wanting to modify the files themselves:
sound_011.wav Original sound file 3.77 seconds in length.
sound_012.wav Original sound file 0.29 seconds in length.
**Shouldn't need to be said, but please give credit to the original authors if you plan on modifying either the model or the skin and releasing them publicly.**