Okay,I've seen mention of the HVII and HVIII so I understand what that is.
What the heck is an HVTB??(looked it up High Velocity Throttle Body,it's mentioned that it's for SC applications)
I'm guessing the TB is for throttle body?
Sporting a new one from GM in all it's $600 glory right now,and honestly there is no need to upgrade a throttle body from stock.
Your not going to outflow the CFM rating on it if your not cammed or SC'ed with a pulley etc...
Kinda like guy's with LS gen III engine's that buy the aftermarket MAF's.
It doesn't give you power because it's bigger....
As for a tune,I'm lucky as I tune my own rides,I have a tuning business that serves the Arklahoma area.
Bought the file to do my wife's car months ago,have yet to even download her stock .cal file to adjust though.
Might drop an email to those tuners though and see what they have found wakes these things up.
Only done a few 3.4's as far as V6's go. I mostly stick with black box vortecs and Gen III LS engines.
And you can't "Chip" these PCM's.
While it's possible with the right skills,there is no reason whatsoever to do it unless you want to alter the chip for real time emulating for tuning.
All GM PCM's(and most Fords) from 1996 up no longer use "chips" they are all flash programmable. LT1 engines started being flash programmable a couple years before 96.