If you have a modern turbo-charged car, the exhaust and engine management are the two biggest limiting factors when it comes to making more power.
In the case of an exhaust, the problem is restriction. Generally speaking, Auto Manufacturers are usually pretty conservative when it comes to their exhausts. They rarely put on an exhaust that is mandrel bent, and they will put on a muffler that keeps the noise to a minimum in the cabin, but is also pretty restrictive. Throw in the conventional catalytic converters, and it is clear to see that there is a big opportunity for a performance increase with an aftermarket exhaust.
By the same token, Auto Manufacturers are usually very conservative when it comes to the tune of your car. Keep in mind that when they set up the tune for a car, it needs to work on every car, in all conditions and climates, and in any driving situation that they can think of, which is to say that they will put on a very general tune. This leaves a lot of room for a tuner to go in and adjust the fuel, boost, and timing parameters to get more power out of your car.
Even if you don’t do anything else, a simple re-flash of your ECU can yield a good increase in power, and can actually improve drivability. When you pair this with a more free-flowing exhaust, you can get a dramatic increase in power.
But if you are going to do only one, which should you do?
One thing to keep in mind with an exhaust is that you really aren’t going to get the full benefit unless you put on a turbo-back exhaust (from the turbo all the way to the back of the car). Putting on the exhaust will allow your car to operate more efficiently, but if don’t have a tune for the car, you are still using the stock running parameters which will greatly limit how much power you are able to gain.
Also, on some cars, you can actually run into drivability issues if you just put on an exhaust with no engine management. An example of this would be the 2006 – 2007 Subaru WRX. This car has a 2.5 liter engine, but it still kept the same turbo that the 2.0 liter WRX had. Because of this, the turbo spools up very quickly. However, if you put on a free flowing exhaust, it will sometimes cause the turbo to spool up faster than the stock boost control parameters can control, and you can over-boost.
Upgrading your cars tune, on the other hand, is usually much simpler, and in the case of a Cobb Access Port, you will also have the tune for the time when you decide to put on your Turbo-Back Exhaust. Most cars will also usually gain more power by up-grading the tune compared to just putting on an exhaust. Not to mention that this is usually a cheaper option when compared to a Turbo-Back Exhaust.
For these reasons, our recommendation is to start with Engine Management, and then to add the exhaust when you are ready.