Its the green one with a red strip! Hehe. Just pull out the yellow plug and bend the plug towards the front of the car... it sits on the inside of the plug (when plugged in, facing towards the left of the car). So you should be able to see it when you look around the plug!

 

Thats odd my old car was stock and I managed to get the needle going past the 180km/h and it kind of went back to the 0. So does that mean I was going faster than 180?

Luckily I've got a 320 speedo now!

 

^^ 320!? Mines about 280 I think... try and clock that speedo! Haha, just kidding!