So I went for it and purchased the Alloy craft S2000 diffuser discussed here:
https://www.s2ki.com/forums/sponsor-...ffuser-903746/
I modified the diffuser shape a little ( 3 small sections need to be cutout to fit under a 135 to clear the exhaust pipe and lower control arms) and made my own adapters to bolt it up. Pics below. Was actually easier than I thought and the parts probably only cost me $40 or so. I also used or re-purposed as many of the parts, bolts, and holes that came with the original parts in the kit. The biggest challenge was offsetting the rear part down and inch or so to clear the factory muffler. With a Berk or something similar, I could have omitted that step and it would be flush. I also used the two screw hole locations on the factory lower bumper insert, so only had to create one extra on the left.
If you have any questions on this, let me know. I just did my first track day with this installed and it is sturdy and stable at over 120MPH. Not sure just how effective it is, but...it's actually a real diffuser, not a facade like most so I am going to assume it is doing something...
$300ish dollars well spent, I say!
The main piece with mods (before I did the exhaust pipe cutout).
Jacknut and associated hardware that made connection to subframe easy.
Muffler cutaway.
Underside view.
Rear shot in garage.
Rear shot at track.
