Common upgrades
- Cold air intakes
- Cat-back and axle-back exhausts
- Intercoolers and heat management
- Performance brakes
- Supporting parts for tuned cars
Honest expectations
Some upgrades mostly change sound and feel; others add real power, especially on turbo cars. Heat matters here, so cooling upgrades can be worth more than an intake. Read do cold air intakes increase horsepower? and turbo vs supercharger.