Summarize:

The shocks and springs in the suspension of your car were designed and built with your comfort in mind.  In order to maximize comfort, the suspension allows the wheels to move up and down to limit how much the body of the car is affected by bumps.  Replacing these components with stiffer shocks and springs will compromise some of your ride comfort, but the added stiffness will keep the tires in contact with the road better, thus improving traction when accelerating, braking, or turning.  Coil-Overs are adjustable shocks and springs that allow you to lower the vehicle and stiffen the ride based on your preference and driving style. Many stiffer suspensions also lower the vehicle, which lowers its center of gravity and also serves to improve handling. Anti-roll bars cross the undercarriage of your car at the front and rear to connect the sides of the body and increase the structural rigidity of your car.  Swapping out the stock anti-roll bars with larger diameter replacements will increase the rigidity of your car’s body even further. This increased stiffness helps to ensure the tires remain as flat as possible on the ground to maintain good traction.  When buying anti-roll bars, it’s best to purchase them in pairs so the front and back offer the same level of torsional strength and don’t permit your car to twist under the torque of hard launches or sharp turns.  Anti-roll bars are also referred to as sway bars, anti-sway bars, stabilizer bars or roll bars. High strength tubular steel is often a better alternative to solid bars, which can be extremely heavy. Your suspension has a number of bushings separating moving metal parts, reducing vibrations and helping to maintain your car’s weight distribution.  Unfortunately, the rubber these bushings are made of tends to break down over time.  Polyurethane replacement bushings are much stiffer than their rubber counterparts and won’t wear down the way stock ones will.  Polyurethane bushings will make loud squeaking noises if not properly greased when installed. Bushings can be replaced one by one or kits can be purchased to replace all of your bushings at once. Some bushings may require the use of a press to remove from their housings. Strut tower bars connect the right and left side of your car in much the same way anti-roll bars do, but they are installed on the top of the car under the hood and trunk lid.  These bars directly connect the driver’s and passenger’s side struts, increasing the structural rigidity of the car and aiding in efforts to keep the tires as flat on the pavement as possible during aggressive driving.  These bars make an excellent addition to after-market anti-roll bars to reduce the amount your car leans and twists while turning.  You may not be able to access the rear strut towers to install a bar in the back of some cars. Strut tower bars may need to be removed when working on the engine of your car in the future. One could argue that being able to stop is the most important part of any car’s performance.  The better quality your brakes, the longer you can wait to engage them before a turn, which means maintaining a higher rate of speed longer than your competitors.  You have lots of options when it comes to upgrading your brakes, from purchasing better brake pads to replacing the entire system with larger, heavier duty components.  Aftermarket brake pads are designed to improve your car’s ability to stop.  They use the stock brake components and are a great option for most street applications. Different brake pad compounds are designed for different uses.  Ask your local auto parts store about the options available for your specific car. Kits can be purchased to replace your car’s brake calipers and rotors with larger ones, increasing the friction surface of the brake pad and improving your ability to stop.  It’s important to ensure your wheels are large enough to clear big brake upgrades.
Replace your shocks and springs with higher performance alternatives. Install larger anti-roll bars. Swap rubber bushings with polyurethane. Install a strut tower bar. Upgrade your brakes.