I've had one installed on my 3.8 for over a year. I picked it up for $128 to test with it. Short answer is don't waste your time.
When I installed it I saw a slight increase in throttle response but I chauk that up to having 30k miles on my stock throttle body and it being dirty. I feel like I wouldv'e gotten the same result if I had cleaned my stock TB. The Viper TB doesn't seem to play well with tuners, especially the SuperChips tuner. The only good thing I can say about it is that it is cheaper than the stock TB so I got a spare for about half price. It does run fine with a stock tune, which is how I've been running mine for the last year. Guess I should note here that I run a manial trans. The reason I point that out is because I suspect that with an auto it may not run as well.
"The society that separates its scholars from its warriors will have its thinking done by cowards and its fighting by fools."
Thucydides circa 460 bc - c. 400 bc