Amazing as it is that the most expensive cars on the U.S. market today are also those whose owners have the most likelihood to succumb to the draw of aftermarket upgrades, the desire to make a high priced toy just a bit cooler is difficult to overcome. In the case of aftermarket BMW parts, there are a couple upgrades that are relatively easy to accomplish, even for the do it yourself mechanic, and propel the performance, or at least the perceived performance, to a level that makes the extra time, expense and effort well worth it. As far as an easy upgrade goes, you really can't beat the aftermarket catback exhaust for improving on throttle response, as well as appearances and audio rumble effects.

The overall weight reduction of the system also seems to improve on the overall torque, resulting in at least the illusion of more power. Amidst the benefits of installation of an upgraded exhaust system, there are minor drawbacks such as the noise level of the system, albeit still street legal, when cruising on surface streets, but is well worth it to experience the power of full throttle acceleration in an open course (or pseudo-open course...) environment. Also topping the list of possible cons to the installation of certain aftermarket systems is the tendency to have to make modifications prior to installation to assure a proper fit, or at least a fit that doesn't need adjustment after going through several heat cycles.

There are, of course, several systems on the market that are different in appearance after installation, most of which look awesome and fit the bill of increasing horsepower at the mid range level, although most will not hold the solidity of their sound at full throttle. Overall, the UCC manufactured aftermarket exhaust systems seem to consistently satisfy the highest of standards across the board, but of course, each enthusiast should review the research on his own between manufacturers and check out the opinions of several mechanics who have had the opportunity to install and follow up on the performance of the system before making a decision that will drop another couple grand on the expense of an already pricey toy.

The other most popular aftermarket upgrade system to add to the BMW are coilovers to improve on handling and provide the ability to adjust the ride height. Requiring a lift and a coil spring compressor to facilitate installation, this one is not really a do it yourself project unless you have a rather extensive garage setup at your disposal. First of all, expect to drop over $1500 for the aftermarket system itself, and while the installation isn't complicated and doesn't require a lot of time, without the right equipment at your disposal, you will be forced to have the system installed by a professional.

When installing the rear suspension, it is advisable to set lower the spring perch at the low to middle setting, as the rear of the vehicle sits high and you will need a starting point from which to adjust the ride height, depending on what size wheels you have on the vehicle. To adjust the ride height, once the wheels are back on the car it is possible to adjust the spring perches without having to take the wheels back off again. This is done by using c-wrenches or allen sockets in the threaded perches until the desired front and rear heights are achieved.