How do I change the FIB siren to an Add-On CHP-Style siren?

Hello everyone!

I recently just got into playing LSPDFR and I've been having fun using the SAHP Bravado Buffalo SX (link here: https://www.gta5-mods.com/vehicles/sahp-bravado-buffalo-stx-dls). My only contention is that it just uses the generic FIB siren, and I want to change that particular siren to be the ones used by the CHP.

I've found various examples of it, but I don't know exactly how to replace the FIB sirens, because most (if not, all) of these mods change the default siren that the regular LSPD cars use. I would rather replace the FIB sirens because I don't plan on using the FIB cars at all. Can someone walk me through how to change just those sirens? Once I learn how to change those, I plan on adding the appropriate IRL sirens for the Sheriff and LSPD cars as well.