the OBII is to help control the smog that comes out of your car, it also prevents you from being able to pull the codes from your car. Other diferences include different shaped headers(which is why the 93-95 model aftermarket headers will not fit) as well as different lenght exhaust pipe. Im sure there are much more diferences, but that is all I can come up with for now. You might want to consider going over to probetalk and ask if and how any one successfully installed one in there car and how they got past the obII stuff