Federal Signal TouchMaster Delta for Siren Mastery 1.0.0

Never actually used siren mastery. Is it required?

Where do i install the .oac file do i throw it in the main GTA V file or something else? ps traditional installation 

1 hour ago, winglesschip209 said:

do they use the yelp and wail on police cars they sound like the one from my local ambulance just a ?

I honestly have no idea. I'm not from the States so my knowledge of sirens is limited. I guess it depends from department to department? 

do they use the yelp and wail on police cars they sound like the one from my local ambulance just a ?