The mass of ship components displayed in the "Design" screen when you hover the mouse pointer over them displays a value that is inconsistent with the value displayed in the "Ship Design screen when you hover your pointer over an installed component or over a component candidate for installation. For example, with all of the mass reductions I have researched, an Ion drive has a mass of 9.6 on the Design screen and 12.6 on the Ship Design screen. Other components display identical values, such as the railgun, which shows 7.2 in both screens.
I captured a few screen shots of this and put them up on my dropbox and tried to open a ticket, but got back "wrong department" when I submitted it.