I’ve been running Powerflow shrouds on a few bikes I own and on a few I was testing over the years and as a direct replacement compared to stock, they are as good as stock, sometimes better. The theory on the powerflow is sound and I’m sure that sometimes/somehow it works, with enough flow. Even when running a temperature gauge on the bike and using an infrared thermometer while having one powerflow and one standard shroud I could not tell a notable difference. For sure in slow speed it didn’t mater and I don’t think my motors were tuned up and running hot enough in the flowing speeds to need an advantage in cooling. If your race bike is running hot, these certainly would not hurt.
That said, the durability and fit makes these shrouds a good buy. And cooling advantage is well, cool!