This is how I modified my front grille. I can't say whether it's the best way to do things, but it worked and I reckon my car looks a heap better for the work.

All up I spent maybe $100 on getting this project completed. The price of course may vary depending on how much stuff you've got in your garage.

All up this project took maybe 5 to 6 hours (plus paint drying time). If you knew how to use bog properly then you'd cut down the time dramatically.

The stuff I used:
Hacksaw
Dremel with cutting discs and sanders (not mandatory, but made things quicker for me)
Masking tape
Bog
Two part modelling clay (I find it easier to work with than the bog)
Sandpaper (Can't remember what grades they were, but I used one rough one for initial shaping, and a finer one for detail work and paint smoothing)
Grille mesh, black (Autobarn, about $30 for a sheet big enough for four grilles)
Wire cutters for the mesh
6x 4g screws with washers
Primer spray paint (Grey)
Black spray paint (Satin Black)

Step 1:
Remove the grille from the car. No photos for this - there's enough instruction on here how to do that, but it's easy enough to do. There's four clips along the top edge of the grille. You just need some needle nose pliers to push the tags in so the grille slides off. If you don't have pliers thin enough, then you can just use a flat screw driver and some patience to do the same thing.

You'll end up with your grille looking something like this (note the peeling chrome paint):


Step 2:
Cut out the centre garnish. There are a few thin fins to get through which is an easy thing to do. It's probable that you could just use a knife, but I used a hacksaw to do the dirty work.

The centre part with the badge is a little harder. Again with the hacksaw, but it takes a bit longer, and I was careful to not dig too far into the top and bottom frames (the better the cut, the less bog is needed).

Then remove the entire centre part by cutting through the horizontal fin.

This is what you should end up with:


There's also some rubber stops at the sides of the grille. They just slip straight off the frame. Remove them and keep them for the very end.



Step 3:
Now you're left with the outer frame and remnants of the garnish at each side. You'll need to trim the side pieces. This is where I cracked out the Dremel and cutting discs. I tried leaving as much of the frame as possible; only removing the bits that were visible from the front.



This was a gamble, as I wasn't too sure how strong the grille would be without the stuff bracing the top and bottom. Luckily though it held up well enough so thank to dumb luck!

At this stage, you'll be looking at this:


I cut off the bottom clip bits (at the left and right), but I don't know if that's such a bad thing. The grille doesn't move upon completion, so it hasn't effected the stability.

Step 4:
This is where the bog starts. Please note that I've never used this stuff before, so it's probably not a great looking piece of work from this point on. I used the masking tape to act as a guide so I could just fill the side up with bog until it was pushing on the tape. After the stuff dried, the tape came off and there was minimal sanding required.




I'm not a big fan of using bog, so I then started with two part modelling putty. This stuff hardens just as well as the bog, but I find it to be much easier to manipulate and smooth. After a bit of sanding, putty and luck the back of the grille started looking reasonable. (This photo shows the drill holes for the mesh too - Originally there were going to be about 10 screws, but it ended up only needing 6)



I had a fair bit of putty left over, so I sealed up the front of the grille where there was a slight gap between the outer frame and the inner.



Step 5:
Now I cut out the mesh. This was a simple case of laying the mesh on the back of the frame and marking where to cut. Using the side cutters I just proceeded to trim off the part I wanted. I left a bit of overhang all around, which I cut back tabs into and used to secure the mesh to the frame.



The tabs were folded down against the frame to give it a bit more rigidity. I don't know how worth it was doing this, but most of this project was guesswork anyway...

At this stage, I drilled holes in the bog so the mesh could be secured properly (the photo with the holes is above).



Step 6:
Once this was all done, it was time to paint it up. I put up a basic spray jig so I could get to all sides of the grille.



I then closed the garage (no overspray for me!) and hit that thing with my primer.



Gave it all a test run...


Sanded the primer back and gave it a shot of the black paint.


Sanded again and gave it a second coat. I left the screws (but not the grille) in place so they would get a nice coating of black when it was completed. I also put the rubber stops back on after the paint dried.


This is how it ended up:


Step 7:
Put it back in place. This is easy - Just click it into place.

Step 8:
Marvel at your handiwork!




Step 8.5:
I took the RS badge off the back of my car, and am thinking about attaching it to the grille. I'll probably use just some double sided tape; maybe some bog/putty. I haven't really decided the best way to go. This is what it will look like...





So that's how I did it. There are some flaws, particularly around the inner curves of the frame, but that's because I'm no panelbeater. As it's dark in there though you have to be looking for it.

Hope this helps.