By Glen Konoroski
Recently one of our crew decided he would make some performance modifications to his 2001 BMW 330 coupe. After some discussions, it was decided that the best place to start the changes on the car was with the exhaust system. This modification would allow the engine to route the exhaust gases out better and be capable of working better with other changes he may make to the engine in the future.
The exhaust system he chose for the 3-series was the Borla cat back system. This system incorporates twin two-inch pipes right back from the Catalytic converter on through the resonator to the muffler and out to the twin tipped tailpipe. We all agreed that the Borla system has to be one of the best-looking exhaust systems we have ever looked at. Everything is made of T304 Stainless Steel with mandrel bent pipes and flawless welds on the resonator and muffler areas where the pipes meet. Even the clamps supplied with this million-mile guaranteed system are impressive looking as well as being made of stainless steel.
Once the stock exhaust system was removed, we were all surprised to find out how much lighter the Borla system was. With a quick trip to the scales we found that the Borla system was about half the weight of the stock which was a savings of over 16 kilograms. Removing the old system and replacing it with the Borla was pretty straight forward and took us about 45 minutes total.
After the system was mounted we found that there was a slight rattle in the system when the car was driven hard. Getting the car back on the hoist we found that the resonator was slightly larger than the stock unit. With a few spacers and washers placed in the right positions the rattle was eliminated.
I’ve found during testing over the years that many of today’s cars like the BMW have very well designed exhaust systems right from the factory. These systems are designed to give the vehicle the maximum horsepower within stock engine specifications. Once these specifications are exceeded the factory exhaust tends to be less effective and limits power output. So, at this stage in our modifications we have found only a very slight gain in power at the bottom end of the power cycle.
What we have gained for the moment is an exhaust system that is lighter, looks great and sounds a little deeper without being any louder that stock. We can’t really say if it has given us any more power, but it does feel much better than the factory system. The price for the Borla system for the 330 BMW is about $1500, and you will find it comparable to the factory system replacement. But, the factory system is heavier and does not have a million mile warranty. You can get a Borla system at most performance aftermarket stores.