pre98 zetecs have the resonator in the engine bay. you unbolt it where it hooks up to the car up front. then dremel or saw it off of the intake pipe. you then have to buy a peice of rubber pipe to put around the pipe b/c it leaves a hole there. you have to cut the rubber to go around the sensor as well. there is also a resonator in the fender well. remove the wheel well lining and take it outta there. it has one torx screw near the back that is hard to get to, but it pops right off of the air horn part of the intake. look in the zetec forum at pics of my car and you can see my intake has no resonator. also has no plenum on the throttle body.
also has no stock air filter.
