I'll take any publication from Autosprint this year with a pinch of salt, especially citing numbers like 0.4 seconds - such general number is extremely hard to predict, although that's what the public understands as metric - "0.4 seconds faster per lap compared to their usual benchmark time".
1. What is the benchmark / baseline time?
2. Lap of which track?
It's the same when you download a file and some state: "Speed: 3 megabytes per second" - not true, network throughput is being measured in megabits per second, and that has been the case forever.
Let me throw some wind tunnel numbers:
What would they mean to you?
Just an example of how random the numbers could be.
Anyway, for some reason I don't expect too much changes in Silverstone for Ferrari, just small aero updates, let's see if I'm right.