Lowering the suspension and fitting higher specification shock absorbers would reduce bodyroll, likely improve the contact between the tyres and the road and may improve steering response, but the amount of grip available is largely determined by the size and specification of the tyres. It would also make the ride considerably more firm, so it is a matter of deciding how much of a trade-off you are willing to make between ride quality, handling and grip. The Nissan Note is not a car renowned for its handling prowess. Ground clearance is 131mm, so reducing this to 101mm or 91mm has the potential to cause grounding issues, although this of course depends on how tall the speed bumps that you regularly encounter are.