The BMW 330ci is the two-door version of the 330, where the "c" stands for "coupe" and "i" for "injection." The model was produced from 1999 to 2005 and is highly prized among enthusiasts for its balance of power, handling and comfort. Aftermarket parts are readily available for the engine as well as suspension, and an extensive network of enthusiasts will gladly share ideas for getting more performance from your 330ci.
The engine of the BMW 330ci is a computer-controlled modern power plant. The ECU, or electronic control unit, at the heart of the engine controls all critical engine parameters. You can obtain a significant rise in power by simply downloading a new program onto this piece of hardware. Many tuners specialise in this type of upgrade. Some will make changes to your car while you wait, while others require you to remove the ECU and send it to the tuner, who will then mail it back to you with an upgraded program.
In addition, cold air intake systems will allow the engine to breathe better, while less restrictive exhausts will allow for burnt gasses to exit the engine more easily. Both modifications add power and make the engine sound better as well. For more radical engine upgrades, a new set of headers will further aid the airflow from your engine, but they must be chosen carefully and installed professionally.
The second part of the performance equation is weight. The less weight the engine has to push forward, the quicker your car will move. However, weight-saving modifications tend to be more expensive and should therefore be attempted after you have performed basic engine modifications. A good place to start is lightweight alloy wheels to replace the stock units. A carbon-fibre bonnet and boot lid should be next on the list, followed by lighter-weight racing seats for the driver and passenger. If you are willing to permanently give up the rear seats, you can remove them and save a good chunk of weight. This also opens up enough space to install a racing-style roll cage, which will provide protection in rollover accidents and further stiffen the chassis for better road feel. The cost for this upgrade, however, is substantial.
Upgrade the Suspension
Cars intended for daily driving, such as the BMW 330ci, use softer suspension settings than what are ideal for performance driving. By simply changing your springs and shock absorbers with stiffer units, you can improve the grip and handling of your vehicle, albeit at the expense of comfort. If you are not afraid of potholes and driveways, these stiffer springs can also be shorter, which will drop the ride height of the car. This will further improve handling, but you risk hitting the bottom of your vehicle on bad roads and driveways. An additional step in suspension modifications is the installation of stiffer anti-roll bars. These will ensure higher cornering speeds, but like stiffer springs, they will make the car less comfortable, especially on rough roads.