Dingpao

What's on your miI have a 2003 Lexus IS300 and the check engine light came on, it requires a front catalytic converter, I took it to a shop and they said i need to just replace the two front ones. They said I have to buy the oem version in order for the check engine light to go off. Do I really have to buy oem? I found an assy by Eastern will that work and its direct fit to the 2003 IS 300 standards, please help or recomend.nd?