from what i know of these it is simply a resistor or sorts that changes what your air flow meter reads forcing the ecu to pump more fuel, it's not that simple to get better performance however.
The only two simple options i know of are the Apexi power FC or SAFC II. these both allow a programmable fuel mapping and will get better economy and performance.
ask yourself "if it seems to good to be true, can it really be true" especially for that price! i'd be very wary of it. do they warrant any damages to your ecu as a result of this cheap device shorting out or damaging your cars ecu?
I really just dont trust the site, besides all the supposed positive feedback from buyers. Considering i havnt paid off the car yet, i dont want to be stuck with having to pay for hefty repair costs. I did find another chip on ebay which is a little more costly. However im wanting to know if there are any other IS200 owners out there who have chipped theirs? And if so what ones did they go for and why?