Designed to improve power, handling, or braking.
Examples:
Mod Benefit Notes
Cold Air Intake Increases airflow = more power Easy DIY for most vehicles
Exhaust System Improves flow, sound, and power Can affect emissions legality
ECU Tune/Remap Increases horsepower/torque Best done by professionals
Suspension Upgrade Improves handling/stability Coilovers, springs, sway bars
Brake Kits Better stopping power Track or aggressive street use