If you've bought a KMH to MPH gearbox thingy, then you don't need an overlay. All you need is the neat sticker with 'MPH' written on it to stick over the word KMH on there currently.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball