"They also said that anything newer than '96 has to have oem cuz of some chip."
Remember, cats are dumb - just exhaust in & exhaust out. As long as it fits in the envelope of the original and doesn't cause more back pressure than the original, then all of the emission control will not be affected.
As for Federal regulation making it illegal to use anything other than OEM - even my Golden Retriever didn't buy that.