The first mod that should done to any vehicle is a spoiler kit in the GT Auto department. They cost 1,200 credits and give the greatest value for the money. Choose the ones to the far right, as they have the greatest downforce characteristics. Most cars can get a kit installed. Save money and do not purchase a Stage 3 NA kit and a supercharger, as they cannot be installed at the same time. Also, when going for the turbo upgrades, look for a fifth kit called "Original". This is usually cheaper than Stage 4. If you have the money to get this straight away, it is better to do this first, as it does the job of Stages 1 to 3 combined, and then some. A recommended strategy for a broad spectrum of cars is (in order): spoiler, full custom gearbox, computer chip, full custom suspension, NOS, race exhaust, then start on the engines.