I decided to replace the original hard drive with a SSD drive , trying to get a high gain in overall performance.
It was easy because the guide is very clear and very well documented.
The only difficulty was with the TR6 screws, because I do not have the proper screwdriver. But I followed the trick of using Dremel to remove the safety part, and after that I was able to go ahead with the T6 screwdriver.
This operation is easier than it seems at first glance. Come on!