After a request or two, here's how to do it.
Front Bumper Removal
(performed on hatch, but sedan is similar).
Tools required:
1) small/medium flat blade screwdriver
2) Philips head (cross head) screwdrivers, 1 large, one small/medium
TIP: You needs a short handle for under the car work.
If you have a small electric screwdriver like a Bosch Ixus or a larger one capable of a 90 degree bend, it'll be faster and easier.
You need the long handle Philips head to unscrew the fastener on each side of the car that connects the bumper to the wheel arch body panel.
3) Small needle nose pliers (not essential, just makes wiring loom plug removal easier...)
Terminology: This is what I call stuff, so feel free to correct me with the right terms, should they be necessary.
1) Shroud - the flexible plastic covers you'll be undoing (but not removing).
One each under the wheel arches, and one larger one underneath the car.
They seal the engine bay and possibly provide some minor aerodynamic function.
2) Expander bolts - those crappy plastic 'bolts' that expand a connected sheath to hold themselves in place.
Used all over the car. Be careful with them, they're not designed for multiple removals...
Safety:
It's recommended you disconnect the negative battery terminal first.
There are electricals in some models (fog lights, temp sensor), so if you don't know how to handle these properly, disconnect the battery and do it in safety (it's not a risky procedure, but better to be safe than sorry!)
You'll be crawling under the front of the car, but there's no need for jacks.
Needless to say, handbrake on, car in gear/drive (even if only parked on a small angle) and wear some safety glasses to stop crap getting in your eyes. There's sharp bits of plastic everywhere you'll be putting your hands, so consider mechanics gloves. In general, don't rush or force anything and take care with anything you undo - don't lose the screws and lay them out in order of disassembly to help you remember where they came from!
Preparation:
You'll be under the front of the car, pulling off a very expensive bumper bar.
Put something down (I used cardboard packing boxes - not too thick, provide some level of comfort to lie on, and are an ideal surface to place the bumper on when you've removed it).
Four main screws hold the bumper on (two near the bonnet release latch, in the top of the bumper, and one each in the underside of each wheel arch, where the bumper and the wheel arch panel meet). With the added help of two clips in the front of the bumper (large-ish) and two small plastic expander bolts (hidden under the rubber bumper support gromits) there's only 6 points holding the bumper on... The other screws mentioned here just hold the shrouds in the wheel arch and under the car in place.
Check out the diagrams below (technical) and the photo reference.
OK, let's get it on!
1) Under bumper: lower plastic shroud
Lie so you can see under the front bumper. You'll need to remove all the black screws running along under the front edge of the bumper. They hold the flexible plastic shroud under the car to the front bumper. There's 3 screws on each shroud connected to the wheel arch, 5 along the front shroud - plus one 'gold' coloured one in the middle. Take note of their locations and how the shrouds interlock with each other. You'll be putting them all back in at the end.
At this stage, though not essential, you should reach up under the wheel arch shrouds and disconnect your fog lights. If you don't, it's OK - you can still do it when the bumper is off. If you don't know how they disconnect, it'll be easier to see once the bumper's off anyway.
Once you've removed all the screws, move round to the wheel arch.
2) Wheel arch: plastic shroud and bumper mount screw
Remove the two plastic expander bolts in the front of the wheel arch shroud. This is made way easier by turning the wheel you're working on 'in' to full lock. If you can jump in the car and do this for each arch, it makes removal of the wheel arch shroud bolts much easier. Don't forget you may have the car in gear. At this stage, the shrouds (wheel arch and under car shroud) are flexible and can be pushed out of the way to make removal of the next screws easier - but be careful with them, you need to push them around a bit in the next step, but don't want to fold them over and permanently bend them.
Now here's a tricky bit: right at the joint of the bumper and body panel in the wheel arch is a bolt, vertical and pretty hard to get to (marked '3' in the diagrams above) - you'll need the long handled, large Philips head screwdriver for this. I suggest you lie and look up under the edge if the arch, pull the shroud away and have a look for screw. Once you've located it, it's tight, but will come out easily.
The edge of the bumper can then be pulled out.
It pulls away (not forward) out from the wheel arch, and will hang out like it's busted.
Perfect, now repeat for the other side, then move on...
Open the bonnet.
3) Under Bonnet: top bumper screws & expander bolt
On each side of the grille area, you'll see a large-ish black screw on the panel with a bonnet support rubber gromit next to it. Unscrew the screws (they'll be tight). The gromit has two parts, a rubber bumper on the top and a plastic expander plug underneath, which slot into each other to make one unit. Pull the rubber gromit out sideways - gently, it slides out of a groove. The top of the expander bolt remains in place. Use the small/medium flat blade screw driver to lever up the expander bolt, which should come out easily now the gromit has been removed.
You are now ready to lift the bumper off.
The only things holding the bumper on now are the two plastic clips in the front plastic mounts inside the bumper itself. Standing directly in front of the bumper, reach down with both hands where you see the two plastic brackets holding the bumper to the front cash structure - the mounting feels like two hand grips, and you can push the clips with your thumbs. Press the clips in and pull the bumper forward.
Voila, the thing just comes off in your hands and you're ready to put the bumper on the ground - be careful because the wiring is still attached, if your car has fog lights and other sensors...
4) Wiring loom removal (for cars with fog lights and sensors)
There are, on cars with fog lights and other sensors, several small rotating clips that hold the wiring in place. They cannot be undone (they're zip-ties and cut off) but can be pulled out of their mounts with small needle nose pliers. Grab under the clip and lever it out slowly (they have those crappy expander bolt fittings...) they'll pull out and can be clipped back in on assembly very easily.
For more info and pictures please see link below:
From mazda3forums.com
http://www.mazda3forums.com/index.ph...2207#msg612207 
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