so i have to train my vocal skills at home when i am not practicing with the band and i do several things to train my voice but i think i also need some extreme metal instrumentals. death and black metal songs are welcome but i would prefer thrash and crossover or hardcore stuff because that is what we play. also i am only looking for songs that actually feature vocals in the original version so i can sing along to it. i know sepultura have done it but other than that i have no idea. also i have the equipment to blast it as loud as possible and record my voice to it without being heard by anybody so recommend me some heavy crushing shit please. thanks in advance.

I don't really know what category you would call it but A Thousand Hands Upon The Maid of Ruin is a pretty good one. Completely instrumental.

http://www.youtube.com/watch?v=QOb6JSQd-Qw

Here's "Frantic Disembowelment" by Cannibal Corpse, if your interested. It's not an instrumental, but the vocals are absent.

The only release I think you will need is "Lethal Legacy" by Mastery (Can),fantastic thrash album with no vocals whatsoever, apperantly they could not find a suitable vocalist so decided to do with out, if they had a a good vocalist they would certainly be up there with the best of them, def worth checking out and just what you are looking for.
http://metal-archives.com/band.php?id=45731
http://www.myspace.com/masterymetal

Relentless Beating from Cannibal Corpse, off of their album Vile

all instrumental and all brutal

http://www.youtube.com/watch?v=qlKvixoMbcE