With the antenna farther forward the correction will be seen the quickest. For example on a 4wd articulated tractor if the antenna is on the back of the cab when the signal comes to turn the tractor left the antenna will actually swing right a little. Not the best situation. When the antenna is at or nearer to the front steering axle as soon as a correction is made to the left the antenna moves left and the computer says "I'm ok now, I moved to where I should". We have threatened to make brackets to extend the antennas a couple foot in front of the cabs and intend to do it this winter. We run the antenna on the nose of the hood quite a bit on our planting tractors where we need good accuracy but that is a compromise because with the antenna below the cab the cab metal probably causes some multi-path in the signal thereby degrading accuracy. Move your antenna as far forward as convieniently practical.

John