To get the most realistic sound you need to go to:

1. Go to C:\Program Files\Rockstar Games\Grand Theft Auto V\plugins\LSPDFR\PoliceSmartRadio\Audio

2. Overwrite "PanicButton.wav" with this file.

3. Go to Rockstar Games\Grand Theft Auto V\plugins\LSPDFR\PoliceSmartRadio\Config\PanicButton.ini

4. Change this line of code from SoundDuration=450 to SoundDuration=8000

Start GTAV and Enjoy!!

don't forget to back up your original files!

Any feedback would be massively appreciated as this is my first Upload!