contemplating a wholesale RE-DO of the underbody... possibly even adjusting some of the exhaust accordingly as well... I want it to be more efficient/functional than it is now and a "better" final product. Not satisfied with how its held together currently either.
I would be ditching the OEM plastic panels in favor of one large solid sheet of aluminum for either side of the car. Potentially one piece that extends the length of the car from the back of the beatrush undertray to the rear diffuser.
I would also have a sheet metal shop give me an inch tall vertical lip down the sides for me to attach rubber skirt extensions to.
But before this, I would want to adjust the axle-back such that the pipe under the rear subframe is lifted up a little (out of the airflow) and the rear muffler is shifted upwards into the cavity left by the (rather tall) OEM muffler
you can see here in this picture that only the right side of the diffuser is acting as well as it could be. With the exhaust hanging low in the center section, the turbulent air is causing enough airflow separation to keep the middle section dry during the rain. The left section is completely compromised by the muffler and is out as well. If I can shift the exhaust pipe in front of the diffuser upwards, and the muffler out of the diffuser, I stand a chance at all three sections operating as well as the right side...
Now, the diffuser is still "working" as I have clearly seen an increase in the amount of water carried up (vertically) visibly behind the car in the rain, but its not working nearly as well as it could be. This bothers me to no end... That and the construction of my existing system is not as solid as I would like (sometimes rattles here and there), and fitment isnt great in places.
I am now well past the "does it matter" stage, and well into the "can I build it better" stage. I am still working through what capability I have to correct some of the issues, but if I can find a way to build this better without having to do anything to drastic, then I will have to try.