Airflow will always take the path of least resistance.
If one pipe alone has the potential to provide enough airflow, assuming the filter is not a restriction, then two pipes with two filter give double the headroom for airflow/power potential.
On a bone stock car, this intake will likely show no gains. In fact, our dyno test showed only a 1-2 hp improvement, which is not really worth mentioning. The stock airbox and filter are simply "adequate" for a stock engine.
Once you chip the car, however, and the ECU is now specifying 20 PSI peak boost output instead of 10PSI stock, you have doubled your airflow requirements, which will easily exceed the capacity of the stock airbox and filter to provide sufficient airflow. While a single highflow air filter can indeed show an improvement, it can still become a restriction at certain airflow levels.
Our dyno testing, on a Stg. 2+ FSI car making a steady 25 PSI with a fuel pump and wastegate upgrade realized a 10 whp gain over the stock airbox and filter with a single cannister version alone. Adding the second filter/cannister realized yet another 6 horsepower at the wheels on the same car, on the same day, still strapped to the same dyno.
An engine is just a big air pump. Plain and simple. As your airflow requirements go up with each subsequent modification you make to the car, being able to support that airflow is important, and this intake provides the most possible headroom.
