Sti gauge reading off
The setup: 03 wrx wagon, tried to strip the green off the gauges, broke the needle, had some extra money lying around so i purchased an STI gauge cluster off a 2004, installed it just fine, and that's the end of that. Fast forward 3 months, I let my dad take my car out for a cross state drive, he ends up calling me saying that at, using a GPS to test mph, when my gauge reads 85 i'm actually going 80. I had assumed that with the sti gauge going to 160 mph, and the wrx only going to 140, that the car would adjust itself. Is this completely off base ad my speedometer only goes to 140, but that is distributed across the 160 scale?