Very likely what that chip does is that it fools the engine into thinking its running rich, so it cut back on fuel and make you run leaner... or so thats what most "performance chips" do. My advice like most likely everyone else in this board is stay away from it before you damage your engine.
If you truly want to upgrade your ecu, try your hand at other proper systems be it stand alone like Megasquirt or a piggyback. If you want to save gas proper car maintenance get the job done.
I know that its sounds tempting for that price, but all you'll be doing is risking your motor and wasting money.