I can’t speak specifically to the Superformance, but my Mk4 FFR ha been soaked several times. My Rod Top works great, but the car still leaks some. The windscreen side bars are a big leak point. I’ve siliconed them like crazy and they still drip some. The door gap at the cowl becomes a water channel at speed, but I’ve found small hand towels folded at the lower corner of the windscreen absorb most of it. I’ve spent some time with the wipers and they actually work pretty well. I’ve worked on the trunk adjustment and it stays dry.
As evidence, here is a video driving home from the mountains in North Ga. It started raining in Blue Ridge and didn’t stop until we got to Valdosta for the night.
As mentioned before, ponding water is a big threat with our wide tires. Slow and cautious is the key.
Safe travels.
John
https://youtu.be/srcA8T0qpvg