i have just done a mph conversion with the thing you wire in to the back of the speedo £65 , the car for some reason seems to drive much better! but i think the speed is still abit out if someone is doing 30 im doing 25 ???is this normal with this conversion

I dont think so, mine seems to be fairly accurate.

 

Mine is wired into the back of the instrument cluster also, a little black box, I dont know where it was bought from, it was on the car when I bought it.

 

John

Mine seems to be a little out aswell.

i have just done a mph conversion with the thing you wire in to the back of the speedo £65 , the car for some reason seems to drive much better! but i think the speed is still abit out if someone is doing 30 im doing 25 ???is this normal with this conversion

 

That probably means yours is accurate and the care you are following reads high. Since my car has stock wheels I've been driving past GATSOs at the correct indicated speed and it's not setting them off... (phew)

 

Strangely everyone else feels the need to drive past them 5mph "slower". I know one or two people on here have checked it against GPS and the Z's clock is usually a couple of per cent under (not over.)

 

Erm... don't rely on that theory though. :D Especially if you've got big-ass alloys with big tyres.