OUCH..you were a little harsh there Daman...LoL.
Waste your time with a Jet Module? The Jet Modules provide some measured increase in performance, you can take it off when you want to, possibly resell it if you need to -- so it's not a bad item for the average owner.
The trifecta tunes appear to be good -- I don't know of anybody getting one personaly either so I can't give any feedback other than what some posters have provided. My opinion on getting a tune, that you insert into your ECM, is that you run the risk of throwing away your warranty because a good technician can find the tune and get your warranty voided. Additionally, if your cobalt needs to be taken to the dealer for work it is possible that the technician can upload new data into your ECM (just a normal upgrade pushed into the field, for example) that would overwrite your "tune".
Until I see a comparison that proves one is absolutely better than the other I'll stick to the "EASY" one...LoL!
To the OP, there is also the MRZ underdrive pulley (UDP) that slows your alternator and AC compressor by ~10% (need a 1" shorter belt that they also provide).