Excellent Hamwich, good to know I'm on the right.... T-Trac

Be aware that this will make your speedo read 5% low. i.e at a reading of 60 mph you will actually be doing 63mph, which is not the way to be if you wish to avoid points on your licence. You will need to recalibrate the speedo to get it maybe 3% or so the other way.
Unless of course, your speedo currently reads on the fairly high side anyway, which would not be unusual!