Install: OEM Undertray (w/U-Brace Delete)

Most people seem to remove their undertrays but I like them. They keep the elements out which in turn keeps the engine bay cleaner for longer. They probably have some aero functionality as well. 

My WRX didn’t come with an undertray when I bought it. And after I deleted the U-brace I wasn’t sure if I was ever going to run one. However, a friend was cleaning out his garage after he sold his Bugeye and gave me his leftover undertray.

So, with the undertray and my old U-brace in hand, I decided to remove what I could from the U-brace without adding too much weight back.

The first thing that I wanted to figure out was what I needed to keep from the U-brace. 

Then I marked the locations that lined up with the undertray so I could easily see what I needed to keep.

Using my grinder, I basically skinned the bottom of the front portion of the brace to for the forward mounting points. Make sure to cut around the radiator support tabs, I almost screwed that up.

Here is the underside of the main piece. 

Now we turn our attention to the rear mount. If you have the full undertray then these are the middle mounts. I wanted to cut out the spacer with a piece of the U-brace intact like a little tab.

I cut out just enough material to mount the undertray to; you don’t need much, the undertray is pretty light and the steel in this portion of the U-brace is pretty thick. The other side of the “spacer” is held on with a couple of welds. 

With both spacers and their tabs cut out, I just cleaned them up a bit. I didn’t put a ton of effort into this as I would like to remake them out of aluminum one day.

Next step I was cleaning up the edges and attempting to flatten out the front piece, so I bolted it to my workbench to keep it from moving around.

And then I hammered out that big dent on the passenger side of the mount.


And painted.

I’ll be honest, about halfway through this project, I found out that Oswald Performance more or less sells what I just made. Now their piece is designed to work with their own U-brace replacement and the rear mounts are different. So I will keep mine. But their bracket is made out of aluminum and is probably lighter than mine. At some point, I will be picking that piece up and ditching my own.


I’ve been running this setup since July 2018. I had intended to post this earlier, but the fall semester started back up and this write-up has been sitting in my draft folder for months. Overall, this is functioning great, the undertray is secure with no issues. I honestly wish I had done this sooner, but finding an undertray was either expensive (shipping) or someone beat me to the punch with the cheap ones. 

Longterm, I have some plans to build an undertray/panel with an integrated splitter. I am still researching that project and one big obstacle is my driveway. My little patch job washed out over the summer as our road much flood nearly everytime it rains. It needs a culvert along with a ditch dug the length of our property and that’s is probably going to cost a pretty penny. 

I am also considering air cups as well, but I need coilovers first. And before I do that, I need to make up my mind on a couple of issues like 5MT vs 6MT; 5×100 vs 5×114.3; or Brembos vs sliders. They all have their pros and cons but the 6MT more or less triggers a snowball effect for me.  


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