There are some modifications that can instantly improve your 0-60 mph times. If the car is still under warranty, and you want to protect that coverage, an exhaust system is the easiest upgrade. [This change can bring] less backpressure and a slight bit more power plus a better-sounding exhaust note. If you want to go further, depending on the age and model of the vehicle, there are plenty more upgrades.
For street cars, take out the extra pounds. Get rid of things you carry with you every day. There are also software upgrades that change the air-fuel mixture and can change the boost on turbo-charged engines if you are looking to build a car, you can race and drive daily, which I have done for years. This [upgrade] will impact the resale value and void the factory warranty.