My old Zed fyi was supercharged (436Bhp@fly) and although I did buy a Stillen engine damper I never ended up getting it fitted, ...honestly it'll be a waste of money imo for you to buy one Oversteer. I never needed it and just let my Zed run on it's OEM engine mounts which was fine even with it being FI.
Personally if you want to improve the drive for the gearbox maybe think about having the oil changed if it hasn't been done already by the previous owner and maybe even the diff oil as well.
I noticed an improvement just with this alone on my Zed, ...used to be difficult going from 1st-2nd and from 5th-6th but after the gearbox oil change with added Molyslip there were no more gear change issues.