The siren is the sliding synth, I can hear it too, lol.
Not much criticism for this tune, it has a real full sound to it and I think the idea was good and it was executed well too. The bass has a real full sound to it, which is refreshing. The mixing is pretty much right on, in my opinion. I wouldn't change a thing about it. I think it was mixed very well.
Percussion was good, seemed to fit well. Not much else to say really...it's a great track keep up the great work.