Here's a video of my BRZ in a Wet Autocross:
There were 9 cars in my class (mostly Honda Integra DC2 and Renault Clio RS/Sport) and I placed 2nd behind a Honda Integra DC2.
(This took place in Switzerland near the French boarder. They call it Slalom and not Autocross here.)
At the long right turn which starts at 0:45 I should have driven full throttle and shifted in fourth and I could braked later before the chicane at 1:09 and at 2:31. But I was concerned about those puddles and possibly trashing an almost new car. After all 3 cars crashed in the woods and 2 cars on that concrete zigzag section at the end.
I ran on Toyo R888 235/40 R17 on 17x8 (stock suspension). They are better than I thought they would be in the wet.
If you follow the steering wheel movement, you can see that the rear broke out many times. I drove in VSC Sport mode.
Since changing the sway bar in the front is against the rules, I haven't given up on the idea of running a staggered set-up (I wouldn't consider it, if changing the sway bar in the front was allowed).
I also think about changing the shocks and running them stiff in the front and loose in the rear.
PS: Sorry about that sound quality. I think the plastic housing of the camera is responsible for this.