Good idea, shitty tone...
Well, I think you should probably add a little bass for the lower parts.
Also, since you have Slayer 2, I'll let you in on a little hint: Start with a clean lead; no effects, cabinet, amp, anything. Run that through FreeAmp3 by FrettedSynt and use one of the drive presets; it sounds a lot better.
Another note: some palm muting would be nice. If you're using a midi file, insert a modulation control change of 64-88 for palm on and 0 for palm off.
PS: Didn't bother to mute while writing this, and now my ears are ringing.