GPupdate and Autosport noticed that traction was a lot better on the Ferrari during the last two days of testing, whether this is due to the new turning veins, floor upgrades etc time will tell.
Also with reference to the first test, that extension may be attempting to replicate the new exhaust housing.
The Acer housing will remain with a editing of sorts to incorporate the new exhaust system/engine housing

If someone said to me that you can have three wishes, my first would have been to get into racing, my second to be in Formula 1, my third to drive for Ferrari.
Gilles Villeneuve