To be honest I'm pretty pissed off about this whole speedo thing not reading correctly. I've had my BK MPS 3 for less than a week and noticed pretty quickly that the speedo is reading more than the actual speed (it's very obvious). I've rang Mazda about this before and they say they've done this on purpose for regulations, etc (can't remember exactly what she said).
If you're anything like me then I usually do 5 to 10kph more than what the speedo tells me so really, I run the risk of a speeding ticket. They should've just got it fairly accurate at the start so we know exactly how fast we're going.
Anyway I'm taking the car into Mazda for a warranty job tomorrow so I'll definately mention this to them and see what they say. Hopefully they can do something about it but I don't like my chances.