Addon Vehicle & Police Scanner SFX Pack

This modification largely expands GTA IV audio in 3 areas: Engine sounds, Horns and Police scanner dialogue.

Video preview: https://www.youtube.com/watch?v=WdKPDL902w8

It has an innovative installation method that does not replace entire .dat15 file. Instead, it loads the metadata as its own DLC, meaning it's fully compatible with any mod that replaces sounds.dat15, such as radio downgraders.

Below is a general breakdown of each part. More detailed information including sound configuration can be found in each respective readme file.

Part 1: Engine sounds
12 brand new vehicle engine sounds have been added, covering everything from tuners, beefy muscle cars, vans and complete jalopies. 
Vanilla game’s vehicle audio variety has some noticeable gaps, e.g. there's no small diesel or rotary equivalent, as well as a large shortage of light inline and ricer-esque sounds (while having tons of V6/8-like sounds). 
This mod addresses these flaws - you no longer have to frankenstein the FLA configs to achieve something vaguely sounding with what IV has to offer. Now you can assign new, accurate sounds.
Most of the samples are sourced from Midnight Club LA and NFS Carbon.

Part 2: Horns
Modification includes 28 new horn sounds. Most of them are ports from my Vehicle Horn Overhaul mod for GTA V, a few of them were made by Jeansowaty.

Part 3: Police Scanner
Push your immersion to the max with 201 new police scanner audio lines, including 25 new manufacturer sounds, 27 new vehicle categories and 149 new car model callouts. Nearly every single lore-friendly mod has been covered. 
If you always wanted the dispatch to properly describe your addon car, this is for you. Your vehicles could've never been more seamlessly integrated within the game's world. Huge thanks to Jeansowaty for voicing the dispatcher.

INSTALLATION

Installing new audio banks:
1. Using OpenIV, drag and drop contents of "to POLICE_SCANNER.rpf" folder to POLICE_SCANNER in \pc\audio\sfx\police_scanner.rpf, where rest of the sound banks are located.
2. Using OpenIV, drag and drop contents of "to STREAMED_VEHICLES.rpf" folder to STREAMED_VEHICLES in \pc\audio\sfx\streamed_vehicles.rpf, where rest of the sound banks are located.

There's 3 methods on how to install sounds metadata (.dat15). Use depending on your scenario. If one method doesn't work for you, try another.
I. Through a custom DLC (easiest method, requires ZolikaPatch):
1. Open ZolikaPatch.ini and set "LoadDLCs" to 1.
2. Drag and drop "Episode3" folder from this archive in game's root folder (where .exe is located).
3. That's it. New sounds should technically exist in your game.

II. Through TLAD (might only work on GFWL TLAD where it's installed in the DLC folder, not the root folder):
1. Open "e1_radio.xml" with notepad and insert following line under "<noloadingtune />": "<sounds content="ascii">e1:/pc/audio/config/newvehsfx.dat</sounds>"
2. Save the file.
3. Place "NEWVEHSFX.DAT15" file from this archive in \TLAD\pc\audio\config\
4. That's it. New sounds should technically exist in your game.

III. Manually inserting custom .dat15 data in SOUNDS.DAT15:
1. Install GTAAudioMetadataTool: https://github.com/ook3D/GTAAudioMetadataTool_V2.
2. Place your "SOUNDS.DAT15" file from \pc\audio\config\ next to ivam.exe and run it.
3. You should now have a "SOUNDS.DAT15.json" file, open it with notepad or similar.
4. Click on line 18 and press enter key (under the first audio entry basically).
5. Open "NEWVEHSFX.DAT15.txt" from this archive.
6. Copy and paste the entire contents of "NEWVEHSFX.DAT15.txt" in your "SOUNDS.DAT15.json" in line 19.
7. Save the .json.
8. In the same directory, create a new text document containing "ivam gen".
9. Save the text document as "ivam_gen.bat".
10. Run the .bat file, you should now receive "SOUNDS.DAT15.GEN" file.
11. Rename it to "SOUNDS.DAT15" and replace in \pc\audio\config\.
12. That's it. New sounds should technically exist in your game.

Now to apply new engine sounds, horns and police scanner lines for your vehicles, check their readme files.