MAKE SURE YOU HAVE mods FOLDER, IF YOU ARE ADVANCED KNOWLEDGE PERSON, SKIP THIS GUIDE.

1) Open: Open IV.
2) Find mods->x64->audio->sfx->RESIDENT.rpf
3) In RESIDENT.rpf, find vehicles.awc and export is as an open format.
4) Use the files in the folder you downloaded and drag it into vehicles folder on your desktop or where you placed it.
5) Now in Open IV, right-click and import open format.
6) Now you are ready to go

I don't know which car uses the sirens in the game, but if you use ELS, use these codes:

		<ManTone1 AllowUse="true" AudioString="RESIDENT_VEHICLES_SIREN_WAIL_03" />
		<ManTone2 AllowUse="true" AudioString="RESIDENT_VEHICLES_SIREN_QUICK_03" />

7) If you want all sirens, you maybe want to rename some of them to e.g. SIREN_QUICK_03 to SIREN_QUICK_02 or SIREN_QUICK_01 idk.