All of them should be able to be 're-tuned'
If you have to go back to the shop that did the original tune, then it may cost 2-300 for a retune. Depends on where you are though.
I never liked the term 'chip' when referring to the tweecer or Moates stuff. These systems use the J3 adapter, so you aren't really working with a chip. Not sure how else to refer to these systems though...
In my mind, a chip is the 'old skewl' way. A chip is actually removed from the ecu and replaced with a reprogrammable chip.
(At least I think this is the jist of it. This is a little before my time, so it is like studying ancient greek... lol)
Well, those are my (very) random thoughts,
jason