I really don't know what the difference is. I went to the sponsor sit, K&N and didn't get a real answer.

From what I read, it is all about money FOR the gov't. They have to have the products sent to be tested by some group and then get that product certified. Probably something to do with the sensors and computer to adjust itself. Wehere the sensors are placed and sometghing like that. I will try and do some research and see what I can come up with


Oh and just found this. C.A.R.B stands for California Air Resources Board. Another State Gov't agency to take our money and make laws to opress fun.