SP Install:

Open the OIV file with any software that can open a ZIP archive file
Drag the lg28cst26bfolder into GTAV/mods/update/x64/dlcpacks
Edit the dlclist.xml in GTAV/mods/update/update.rpf/common/data
Add the following line - <Item>dlcpacks:/lg28cst26b/</Item>

Now, In order to use the mod do the following:
To use on any car, edit the vehicles.meta, find where the car is defined, and replace this line with either:

(for the Turbo version):

<audioNameHash>lg29cst26btrb</audioNameHash>

(for the na version):

<audioNameHash>lg28cst26b</audioNameHash>

(Original Instructions from Aquaphobic | Changed with his permission )

FiveM Install:

Drag the 'lg28cst26b' folder into your 'resource' folder.
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Premade resource with fxmanifest.lua file strings provided. If using this, don't forget to ensure the new resource in server.cfg.
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To use on any car, edit the vehicles.meta, find where the car is defined, and replace this line with either:

(for the Turbo version):

<audioNameHash>lg29cst26btrb</audioNameHash>

(for the na version):

<audioNameHash>lg28cst26b</audioNameHash>
(Original Instructions from Aquaphobic | Changed with his permission )