The 718 GT4 RS has some nice aero upgrades, including underbody strakes. These strakes help evacuate turbulent air from the front fender wells, reduce underbody turbulence, and seal the floor with vortices along the sides of the car. The end result should be increased front end downforce by making the floor more efficient, and if you’ve got a rear diffuser it should help make that more effective as well.
It’s becoming a common upgrade on the newer Caymans and Boxster’s where they are a simple bolt on affair. On the 987, that’s not quite the case, but the chassis and body of the Cayman and Boxster hasn’t evolved that much between the 987 and 718. Porsche’s engineering on these parts should translate well to the 987, assuming they’re installed correctly. I decided to take a shot at it!
Below are my results, and some tips that may be helpful if you decide to undertake this project too.
Part Numbers
I ordered this as a kit through Suncoast, which did include some extra speed nuts and screws. It may be cheaper to order these individually, so here are the part numbers of the strakes themselves:
- Inner strake L – 9GT.825.487
- Outer strake L – 9GT.807.945
- Wheel well strake L – 9GT.807.945.A
- Inner strake R – 9GT.825.488
- Outer strake R – 9GT.807.945.B
- Wheel well strake R – 9GT.807.945.C
Installation
The installation of these parts is pretty straightforward. 4/6 of the parts will need to be trimmed to fit the 987’s underbody. I mostly used OEM speed nuts and screws to attach them, I cut squares into the underbody panel to slide on the speed nuts.
Ensuring the parts are in the right place and aligned correctly is the hardest part, but after I spent way too long studying GT4 RS photos and renders, I discovered that is fairly easy to get them aligned correctly if you know the tricks.
You will want to install the outer strake, first. The straight line on this strake (red line on the photo below) is aligned parallel with the body of the car and underbody panel. Through test fitting, I found the blue line aligns perfectly with the underbody panel as well, making this much easier to do.
If you look closely you’ll see I installed the side of the outer strake aligned with the red line about an inch or an inch and a half over the edge of the underbody panel itself. I found this matched closest with what I saw on the GT4 RS.
The outer strake does need some trimming to fit, I trimmed the bottom essentially flush and cut off the top mounting hole.
Once you have the outer strake installed, you can install the inner strake. It sits about 5 3/4″ to 6″ from the outer, measured from strake to strake itself.
Finally, to install the wheel well strake. Luckily, there is a straight line you can follow on this one, too. There is a notch in this piece that fits around the pinch weld on the GT4 RS. Make sure that is aligned straight with the car and you’re good to go.
I test fitted mine around my pinch weld, but decided to move it inboard. I felt that it fit the 987 there better matched the install on the GT4 RS well enough. To do so, I trimmed the tip and drilled a few holes.
Below is a photo dump of my finalized installation that should hopefully provide you all you need to picture this on your car, and test fit yourself!
