I haven't listened to the track you posted (it won't load for some reason), but I really think the only thing to do is to practice, practice, practice. I kind of have the same thing - as much as I want to sound like Jacob Bannon (Converge FTW!) I never will, no matter what. So instead, I just found my own scream and had to grow comfortable with it. Once I did, I got some confidence and then took it a bit further.

Lessons could only help. Even if you take lessons from a normal voice trainer, I'm sure they could give you some good tips and help you out.

EDIT: Oh god.

All I can really say, if you're not the greatest troll ever, is to put your balls into it and yell at the top of your lungs instead of screaming like your parents are in the next room. You can't get a good scream at that volume - crank up the decibels and scream like you're trying to scare someone.

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