To be more specific, this issue was most apparent in the DOHC 2.5l NA engines. The EJ25d from the earlier impreza 98-99 and the early year subaru foresters from same years had these issues. If you get a newer model 2.5 from 2000+ the headgasket issue was almost non existent. Keep in mind the 2.5L engine only came in the forester and impreza 2.5 RS from 98-2001/2. (and of course all the newer models from 2002 up but those are slightly different)
The 2003 impreza WRX had a slightly different coolant system than the previous 2002 WRX. It contributed to some weird cooling issues but nothing major.
The earlier model Impreza (98-2001) and forester (98-2002) had almost identical interiors and wiring and shared the same motor and transmission. These years have some weird electrical issues that cause some interior lights to work intermittently. Can be annoying and a PITA to track down and fix.
					The 2003 impreza WRX had a slightly different coolant system than the previous 2002 WRX. It contributed to some weird cooling issues but nothing major.
The earlier model Impreza (98-2001) and forester (98-2002) had almost identical interiors and wiring and shared the same motor and transmission. These years have some weird electrical issues that cause some interior lights to work intermittently. Can be annoying and a PITA to track down and fix.

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