2008 Subaru WRX STi
Stone Guard

I am now at about 700 miles on my 2008 STi. There are a lot of things to like about this car but there are a few things Subaru left off from previous year STi models (like the STi Logo on the intercooler). There are also a few things that Subaru continued to leave to the after market. One of this is a way to protect the TMIC from damage by road debris; a Stone Guard. As you can see from the following photo, the risk to the TMIC is real.

Damage to the TMIC after less than 700 miles.

When I got my 2003 WRX there was a TMIC-mounted stone guard available through the after market. I searched the Internet and couldn't find any protective products even from the same manufacturer that I bought through back in 2003. Even the original product was no longer around. It was clear that something needed to be done before it was more than just a few cosmetic dings to the cooling fins. Sure each ding reduces the TMICs ability to do it's job but sooner or later something more catastrophic was bound to happen; leaving the driver stranded somewhere because of a preventable "event".

I had no choice but to plan a DIY project to tide me over until a commercial option became available. Do you hear me, after market developers? A bolt-on solution would be snapped up in a heart beat even though I have this DIY to tide me over.

After some consideration, I decided that I preferred the cleaner look of the engine bay without the TMIC-mounted design that I bought for the '03 WRX. It works outstandingly and I would get one for the '08 STi if that was the only option but I would prefer a scoop-mounted design like the one that follows.

TMIC-Mounted Stone Guard on 2003 WRX

I had the need and the concept now I needed the plan. I ordered some aluminum mesh from McMaster-Carr but what I ordered was too thick to fit in the hood scoop insert. It would work as a TMIC-mounted solution, but for now I set it aside and went to Lowe's for some expanded aluminum mesh. The pickings were slim (only 1 real option), so, for under $8, I picked up a sheet of mesh that was about 8' long and 3' wide. That means I had a WHOLE LOT of it left over if there's a local Subie owner wanting some for a project like this. PM me through the forums and we'll make arrangements. Remember... it's FREE! While at Lowe's I also picked up a rattle can of appliance epoxy paint for it's durability against chipping. Shopping was done. It was time to gather the other things I'd need.

Above: Stiff cardboard for cutting a pattern. Flat blade screw driver to removed the platic rivets holding the scoop insert in place. Dog-leg flat blade in case some rivets are hard to reach under the sound deadening cover on the underside of the hood. A marker to draw the pattern. Diagonal cutters (dikes) to cut the aluminum mesh.


Remove the scoop insert from the hood by removing the 15 plastic rivets (above) that hold it in place. The inner pin of the rivet locks the outer collar in place. You have to insert a flat-blade screw driver into the knotch in the collar and twist the screw driver to pop up the inner pin. If you try to pry the pin up from the collar (or the collar and pin up together as a unit) the rivet will break. Extras are available through your Subaru dealership if you break or lose any during your project. I need 4.


Slide the scoop insert forward slightly to clear the retaining tabs on the front right and left (arrows). Once the scoop insert (above) is removed set it aside. You can clean it now or prior to reinstallation but it's a good time to clean it and the under side of the hood scoop (below) during this project.


There are 5 plastic rivets on each side. This photo shows the associated mounting holes along the top and bottom but most on the left and right are hidden under the insulation mat.


We're now done with the dissassembly and are ready to start fabricating. Hold the cardboard up to the inside of the scoop opening and draw your pattern through the top/entrance of the opening with the marker. It takes an extra hand (or chin) to hold the hood steady while holding the cardboard and marking the pattern but it can be done. Double and triple check your pattern for accuracy. If you have to, work your way toward a final pattern through several, larger rough cuts that let the cardboard fit into the recesses where the scoop insert mounts.

Mesh and one of the rough-cut patterns

Once the pattern is cut, transfer it to the mesh and cut the mesh to size. I chose to work my way down to the final size through various rough cuts. I did test fits after each rough cut session (measure twice, cut once).


The above photo is one of the rough cuts of the guard. You can see where it's still over sized to the pattern-transfer marked on the mesh. I also cut several tabs that fold "forward" to add strength and lend support. The finished guard's tabs are smaller and line up with the recesses, not the rivets of the scoop insert. The plastic rivets aren't long enough to reach through the scoop insert, the mesh and the scoop and still lock into place during reassembly.

Once done fitting the mesh, I painted it with 2 coats of the epoxy and let it dry. I also coated any of the mesh, that would be in contact with the car, with liquid electrical tape. This will help protect the car from scratches and abraisions. You could also use grip dip but I didn't have any in my garage at the time. I'd choose something in black regardless of what you use. Black hides better inside the scoop.

After a good dry (overnight for assembly and 24 hours before driving IMO), I reassembled everything in reverse order. Once done, it's very stealthy unless you look closely at it.


A good tide-me-over until the after market steps to the plate with this important product. In the photo above, the specs on the scoop and mesh are from the towel I used to clean up before taking the photograph.

Once you're done cleaning up your work space, get a toothpick or two and get to work straightening all those bent intercooler fins. Your turbo will thank you for it.




(C) 1995 - Present, Mark Johnson