At the end of the pantera song, theres that sound like a siren, is it just a artificial harmonic or is it something else?
Its the signature Dimebag squeel....basically pull off to the open G string, dive the bar, and then tap a harmonic on the G string and liift the bar up (Dime explained it better on YouTube, but its a lot easier said than done...)

Crafter FX550 EQL
Ibanez SA260FML

THD Univalve
Framus FR-212 Cab (Celestion Vintage 30's)

Dunlop Crybaby

Started playing May 28th 2005
Hit an open G string. Shove your whammy bar down, and then start pulling up on the bar. when you get to about normal pitch, touch the string on the spot for the 7th fret harmonic, and pull the bar up as far as it will go.
you could also not play the g strings or other strings before dumping the bar, since the strings are flapping and very loose, they tend to move a lot, then just put the left finger(s) on top of a certain fret or wherever you like your left hand to be, and pull the bar till i cant pull no more.

i do that. saves me some more time by not flicking a string before dumping the bar.