Ok guys just got myself very confused. I have the following configuration setup on my X axis
5mm pitch HTD15 belt used:

16 tooth pulley on stepper going to a 72 toothed pulley, on the same shaft as the 72 is a 24 toothed pulley driving the axis with matched 24 toothed idler. What by your calculations should the ratio be? Things are cutting slightly larger than expected in EMC2 :whistling:

Thanks in advance