The 2004 BMW 5-Series is part of the E60 generation of this luxury sedan. The E60 replaced the E39 and was later replaced by the F10. As the 5-Series has evolved, it has also become larger and heavier, and to a certain extent less sporty in the process. Powered by a 225-horsepower 3.0-liter straight six, the 530i is pretty capable in stock form, but like all BMWs, its performance can be improved upon with the right modifications. Keep in mind that a high-end car like the 530i should be modified by a professional shop that understands how to work on these cars.
Reflash the engine software. Modern BMW engines are controlled by complex computers that determine how much fuel, air and spark the engine gets and when (timing) the engine gets it. A reprogrammed ECU will change these settings and allow the engine to make more power. This is definitely an upgrade that should be made by a shop with the proper know-how and automotive diagnostic equipment to avoid damaging the motor.
Install a higher-flow throttle body. One of the restrictive areas on a 530i's engine is the throttle body, which is located on the intake side of the motor and is responsible for delivering air to the engine. A larger throttle body will deliver more air to the motor, producing more power and sharper throttle response.
Replace the stock exhaust. In stock form, the 530i's exhaust system is designed to be quiet and relatively restrictive. Replacing the exhaust system from the catalytic converter back (to retain emissions compliance) with a larger-diameter exhaust and free-flow muffler will allow the engine to run better, make more power and sound better.
Install a supercharger. One of the most effective ways to make a 530i considerably faster is to install a supercharger (see Resources). While the changes listed above will give incremental increases in power, a supercharger will provide a massive power gain. The supercharger is a compressor located on the intake side of the engine that forces more air into the engine for a large power gain. This is also the most expensive power upgrade that can be performed on a 530i's engine and can run around $10,000 for the parts and installation.
Upgrade the suspension and brakes. A faster 530i is not one that simply goes faster in a straight line but one that corners and stops better as well. A stiffer suspension and better brakes are particularly useful on a heavy car like the 530i. Install performance shocks and springs to reduce body roll and then upgrade the brakes with ventilated discs for better heat dissipation and more aggressive pads for shorter stopping distances.
