do those speedchips work or are they just a scam? I found them on ebay just search "pontiac g6"

scam. They just fool your computer into thinking that the incoming air it's colder than it is so it adds more fuel to the mix...it just results in a rich A/F ratio. You might gain a little HP from it (<2) but you are also messing with plugs, injectors, catylic converter...not a good idea to run rich.

it's not worth the gain in the long run.

Mike