eventually i had to take it off. No doubt the upgrade made my printer more rigid.
but, apparently all the vibrations from the Y-axis moved to my X-axis and Y-axis vibrations to Y-axis !!
Before the upgrade i had a perfect X-axis lines and after the upgrade there was some weird lines and ghosting.
even though all belts were perfectly tighten and calibrated.
SO, i took it off and that's it.. Back to perfect Y-lines.