Open the OIV file with any software that can open a ZIP archive file
Drag the rx7bpeng folder into GTAV/mods/update/x64/dlcpacks
Edit the dlclist.xml in GTAV/mods/update/update.rpf/common/data
Add the following line - <Item>dlcpacks:/rx7bpeng/</Item>

To use on any car, edit the vehicles.meta it is defined in, and replace this line with either;
<audioNameHash>rx7bpeng</audioNameHash>

And have fun ;]