Offered for the Impreza 555 are several .INI files containing different layouts.

What never changes between layouts is OilT and Tachometer (First two gauges from the left).

What can be added or removed are the following: 
3rd gauge- Boost or Speedo
4th gauge- WaterT
Gear Indicator(top or bottom)
Shiftlights

The default 'config.ini' contains OilT, Tach, Boost, and WaterT gauges.

The variant config files are located in impreza95\!GAUGE LAYOUTS folder. 
A picture is included to show off the 8 different layouts.
The name indicates what is added; Example: "config.iniBoostWat" will include Boost and Coolant gauge.

To change layouts:
1) Create a backup of 'config.ini' 
2) Change your preferred layout filename to 'config.ini,' select 'Yes' when prompted to replace.