Driving a Mustang is an exhilarating experience that never grows old. Because they are sports cars, they have the get-up-and-go that pins you to the seat; exactly what is wanted when buying a Mustang!
When your Mustang was new the ride was perfect, couldn’t find a flaw if you tried. However, after a period of time the ‘newness’ wears off and you begin to dissect small (real or imagined) problems with the performance of the car.
You can improve on the burst of speed off the line with performance chips, but this does not help cornering. Part of the fun of driving a sports car is the ability to take turns at speeds designed to give a feeling of G-force to the occupants of the car.
If you find that you have to break when cornering then you need to examine the suspension of the car. Suspension balances the weight of the car and occupants, giving the car more stability. Better stability means better cornering.
Stock spring suspensions are fine for a while but they wear out relatively quickly. The best upgrade for the car is to install an air suspension kit. Even brand new stock suspensions do not come close to the comfort of the ride or the stability offered by air suspension.

Air suspension kits are readily available online that have all the parts needed, from air struts to fittings. The best kit I’ve found is the Deluxe AOS (air over shock) kit. It has everything, front-to-back and side-to-side suspension. You will be breathless with joy when you take your first ride after this installation.
Air suspension kits run from about nine hundred dollars to two thousand dollars. The shocks alone are one half the cost of the entire kit; trying to do a piece-meal upgrade will cost you at least one third more than just buying the kit.
Unless you are very mechanically inclined, a professional should do the installation since some parts might require slight modifications.
You will never be sorry that you upgraded your Mustang with air suspension. Feel the G-force when taking those corners!