Its easier if you have ramps and just park with rear in the air. Otherwise get it up on axle stands to allow room to manoeuvre underneath.
Ok, so remove the engine access cover and this is what you see
remove screw/bolt (was bolt on old car...on this one a screw) for top of heatshield
There is also a bolt at bottom heatshield but no pics as mine didn't have one
Now remove the 3rd heat shield bolt..with spacer...this is 13 mm
5 bolts to remove .....15 mm socket
Now remove the heatshield
Looking from under the car , this is looking up through downpipe to manifold from ground
and a closer shot, looking at manifold/downpipe flange (6 stud manifold)
Now remove bolts form manifold/downpipe flange...15 mm. Use an extension bar to reach bolts. Remove 6 bolts
Now remove cat/downpipe bolts. Mine already had cat saver bolts, so is easy....you may have problems if this is first time!1
Now you need to remove the downpipe from the rubber mount...this is made easier by spraying with WD40 or other lubricant first!
disconnect oxygen sensor plug and then remove the downpipe from car...may take some jiggling.
Attach new gasket to downpipe/manifold flange
also new gasket (and firegum style paste to make a good seal to cat/downpipe flange)
DONT add gum/paste etc to manifold/downpipe gasket as it can damage o2 sensor!!
and ..........reverse!
(attach new or old oxygen sensor BEFORE refitting downpipe)
exhaust manifold bolts = 45 nM....downipe/manifold flange bolts = 50 nM...cat/downpipe bolts ...50 nM