This has been beat to death and back. The problem I see is people who REALLY don't know are injecting opinion that only serves to confuse. I gotta believe the reputable tuners have a pretty good idea whats going on but the bottom line is if you're worried or can't pay for a rejected warranty repair DON'T TUNE!
The service manager at my dealer said a CAI would'nt void the powertrain warranty and neither would a cat back exhaust and those two mods made mine run a lot better so stick with whats safe and enjoy the ride!!!!!!!!!