how bad is this
 

If you have a 6 speed, and lets say you turn off ASR and start in first, floor it to 6,000 rpms and shift as fast as you can through 4th gear, all shifts at 6,000 rpm. How bad is that for your clutch, rear, driveshaft, engine, mounts, everything. Just wondering. What can break??

Sounds like a normal Sunday drive to me! lol
Seriously, any one of those components can break when beat on hard. It's just a matter of time, and which one is feeling weak at the moment. But, I'd prolly put the trans mount at the front of the failure line.

everything can break.

Ls1 camaro m6...fast shifting - YouTube like this, the guy misses a shift from 2nd to 3rd. he does another fun and goes 1st to 4th. Besides the missed shift, how bad is the second run for the drivetrain??

its just as bad as doing it on any car, not anything out of the ordinary. When running a car hard, things can happen

ok. I havnt done it much. Ive only done one full our run from 0-125. So what about burnout? reving to about 1500 - 2000 and roasting the tires from there, how bad is that. haha sorry so many ?s

clutch dumps are probably the best way to blow that 10 bolt up, albeit a 2k dump isnt a huge one, its more than enough to ruin your 10 bolt's day. The t56 itself is strong and will take a lot more abuse than you could throw it at with a mild ls1. The clutch would be the first thing to be replaced, it can feel pretty glazed after just a few dumps.

my t-56 has ~25,000 miles on it. And the clutch was replaced, i forget what milage. What if the clutch is out, and you floor it, and jab the brake, not doing a clutch dump

The clutch was replaced with less than 25k on it? wow, that was a shortlived clutch.

I'd be worried about the rear end than the clutch. Regardless of how you do your burnout, it still stresses that 10 bolt. And no, I don't think I am overexaggerating it as I have seen, read and unfortunately experienced the crappiness of the 10 bolt

you missunderstood me. My t56 was replaced, it now has approx. 25,000 miles on it. The clutch was replaced far before the tranny,i just checked my records, the original clutch had 107,000 miles. the replaced clutch now has 91,500.