Calibrating The Speedometer

Does anyone know what needs to be done in order to recalibrate the speedometer? For some reason mine is slightly off, and the amount that it is off by increases the faster I am going. I.e. it's only off by about 1 mph when I am going 30 but when I am going 80 it is off by 5. I used my GPS to check the actual speed.

I am assuming this may be something I need to go to the stealership for but I want to avoid that if possible. :)

What year is your golf?
Franco

It's a 2001 VW Golf MK4 2.0

Well I don't know if it helps but you can recalibrate mk5 & mk6 Golf speedos with VCDS. ;)

https://www.myturbodiesel.com/1000q/a5/speedometer-read-fast-adjustment-VW.htm

Old link doesn't work on the new crap forum