Hopefully I can help clear some things up

That's my writeup linked to, here's a more up to date version
http://www.oqcgp.com/forum/kb.php?mode=article&k=33
LS1 WOT TPSvoltage will vary based on the infamous bump stop milling, but most ZZP units come with low 4.8x voltage.
LS1 F-Body's can't exceed 4.75 WOT volts without throwing a code, our cars don't do that til 4.9 volts.
Our PCMs will commant WOT at around 4 volts, maybe 4.1, I forget the exact number. The LS1 TBs will reach this voltage faster but the WOT voltage is hard coded in the PCM and remains unchanged.
It is a bad idea to tune based on idle TPS voltage, without relating it to WOT voltage. Reason being is that the idle stop screw makes this a variable instead of a constant.
Stock throttle bodies are around .4/4.1 voltages, and are best tuned to 4.32-4.34 WOT voltage, along with 10-15 IAC count at idle (while not exceeding .75 volts).
LS1s I like to set up around 4.82-4.84 WOT voltage, but will usually only touch the TPS sensor if it is too close to 4.9 (eg 4.88). Idle stop screw adjust to 1/4 turn preload on the linkage, just enough to stop and binding in the inner bore. To help idle out, enlarge the IAC slit between the TB and the adapter, as Brent H and I show in the instructions on ZZP's site. Then drill the hole back in the throttle plate to at least original size, larger if hard starting still exists.
I don't have any GP testing of the Northstar TB but my mother's 96 STS Northstar I have set at 4.67 WOT voltage with a .71 idle voltage. I couldn't get an IAC count reading off my Alex Pepper scantool but the car responded well.
HTH and please email or repost if I can help clarify
