What you'll need.
-Si Axleback Exhaust
-Si gasket off resonator
-12mm socket, Ratchet
-Can of PB Blaster is very helpful
-Long flathead screwdriver
-Jack, Stands, Chocks (you really shouldn't be messing about underneath the car if you haven't taken the appropriate precautions)
-A nice warm place to do this. I found a heated garage before the start of my shift is perfect.
Let's get started.
Collect the Si Axleback exhaust and the gasket from the resonator.
Jack the car up using the appropriate precautions.
The bolts that hold the axleback on are located just in front of the rear axle. You will need to remove these.
You may find they don't come off like they were just installed from the factory so you may want to give them a squirt with PB blaster. Alternatively, you can also use an impact wrench or long breaker bar.
Use the long flathead screwdriver to break the muffler free from its hangers. You can also use your hands.
Here are the two mufflers. The Si exhaust has a larger diameter inlet pipe and a much nicer looking tip.
Remove the gasket from the resonator. I used the flathead screwdriver and wedged it in between the piping and the gasket itself. Take care at this point not to damage the original gasket in case you want to reuse it (although a new gasket is the recommended way to go).
The Si gasket on the left, versus the LX gasket on the right.
The resonator sans gasket.
With the Si gasket. It's a little bit loose, and you'll need to sandwich in between the axleback and the resonator until you get the bolts in place. I used the same bolts that I just took off to put the axleback in place.
At this point, once you've got the bolts back in, re-torqued, and the hangers in place, you can get out from underneath the car and admire your work.
Enjoy your car's improved appearance and sound.