I am going to add my 2 cents(maybe 1 cent) to this thread. It is my (basic)understanding that the computer in the viper functions basically the same as any other OBD2 ECU. With the factory positioned front O2 sensor, it senses the entire bank and tells the computer to make corrections. However, it does not richen or lean a single cylinder. It takes all 5 collectively and adjusts the mixture to the entire bank to meet the programmed criteria. In other words, you could have a dirty injector, faulty injector, or some other injection problem, and as long as the mixture wasn't more than a 20% or so correction, it wouldn't set a light. Conversely, you could have a cylinder running way rich with the other cylinders running fine and the corrected mixture would lean out the entire bank just to fix the one running rich. The sensor has no way of identifying a particular cylinder, so adjusts the entire bank. It would take a sensor per cylinder to adjust individually.
Race cars run no O2's at all and are run at extremes continually. If there is a better sensor out there, I will move the O2 back to it's original location as I agree this a better place. In the mean time, my sources tell me the risk is very minimal.
As for the power increase, I picked up around 30HP. And then there's the sound....Belanger headers, no cats, 3" pipe, Walker Race buller mufflers......incredible! Makes the Viper sound the way it was meant to. I don't run heat shields and have had no problem in 10K miles so far. Side sills run much cooler.
Steve