are the chips on ebay that say 20 hp +? are they for real or just a scam?

some work well but 20 hp extra is pushing it

how do they work? do you just plug'em in or do you need a computer to readjust everything. and which kinds would you/anyone reccommend?

Yeppers just remove the bolt from the center of your puther , pull the harness back , Slap the new module in there, line up the slots , an then same with the ole wiring harness connector. Make sure u disconnect the Battery first , Well they all claim to be the BEST ( oh try to discharge any static build-up you might have by touching sonething metal before you put your mitts on the puther )..........

Id bet that most of them do work. Id say that a claim of 20 hp is optimistic. The only problem is that you fuel economy will drop signifigantly. If you want more power you usually have to give up some fuel economy.
Octane