You have to take off your front bumper (two screws in on each fender lip, two bolts behind each bumper signal, and a couple underneath). Now all you have to do is remove the three bolts that hold the resonator in. Two out of the three bolts are kind of hard to see and you are going to need a long socket extension to reach them. Once it is unbolted, pull it out. DONE! Real simple. Might take you 20 minutes.

If you don't want to take off your bumper, you can just take off the cover under the resonator (plastic mudguard that covers under the passenger side fender and underneath part of the front bumper). After you take that panel off, just take off the resonator by unbolting them.

The bolt sizes on the bumper and resonator (at least on my '90 LS) are 10mm and 12mm. The larger bolts behind the bumper signal lights are 12mm and the bolts under the car are 10mm, as are the 3 bolts holding on the resonator. All screws are Philips.