Every time I try to load a siren, the default siren just stays in the game, I've tried multiple sirens and the same thing happens over and over again. Getting extremely frustrated.

Your topic has been moved to GTA V Support, this is not LSPDFR related.
Please post in the correct location in the future.

19 hours ago, Lazershow16 said:

Every time I try to load a siren, the default siren just stays in the game, I've tried multiple sirens and the same thing happens over and over again. Getting extremely frustrated.

What do you mean by "load a siren"?  You can't load sirens.  You have to replace audio files, which most of the siren packs have a 'how to'.

That's what I meant. When I try to replace the sounds files, all the car audio in the game stops working

On 2016-10-04 at 1:06 AM, Lazershow16 said:

That's what I meant. When I try to replace the sounds files, all the car audio in the game stops working

That happend to me aswell, i tried to install Prophet's PA500 (?) together with American Sirens pack and i didn't have any car audio. So i just had to simply install another siren.