I installed an 04' STI gauge cluster in my 04' WRX. All works well even the rpm warning indicator. Dccd light is on and center diff temp light. Using the same year for your swap seems to be the way to go.
But something that people seem to have missed when I looked for this topic was I noticed that when the speedo said 40mph my GPS said 37mph. I figure this must be because the STI has 235/45/17 tires which have a diameter of 25.4" compared to my WRX's 205/55/16 which have a diameter of 24.9".
How can I correct this? Is is a tranny speedo gear or in the cluster itself?
I'd like it to be accurate becuase it will actually rack up the miles faster on my car.
Thanks for your help.