if you are only seeing below 13volts with the car running then the battery light should be on all the time. your test results don't seem to make much sense.
Got it solved. First off, thanks so much for the help gents.
To review for those searching for this solution, car was turning itself off driving down the highway, at high rpm battery light was flickering. I replaced the battery, alternator, and alternator to battery cable.
Upon doing so car was still dying and was still getting the flickering light. Tech at VW advised that I run a single jumper cable from the alternator (where the alternator to battery cable attaches) to the positive battery terminal without the positive battery connection attached. This would essentially allow power to run through the jumper cable and bypass the battery to alternator cable. Assuming your battery tests as functioning properly if the battery does not indicate roughly 13v when the car is off and then 14.5v (or at least a 1.5v increase as suggested in this thread) then the alternator was bad. If a test did indicate the increase in voltage then the cable was bad.
Upon using this test the multimeter indicated no voltage increase when the car was running, indicating that the brand new alternator was bad. I took the alternator into AutoZone tonight and they hooked it up and it failed the regulator test in about 3 seconds.
My brand new alternator was bad... Brought a new one home and it cranked up fine, no battery light, no flickering battery light on redlining, and multimeter test was over 14.5v when the car was running.
The good side I guess was that installing it the second time with experience was a cinch. Took about 20min to pull the bad alternator and about 40min to install the new one.
I guess the really good thing is that this wasn't a VR6 and I didn't have to pull the front end off again to replace a brand new alternator.
Other than now trying to figure out which tube off the intake manifold is leaking and giving me a rough idle, it looks like I'm good to go.
Solved. Again, thanks for the help!