With a downpipe exchange in process there are a pair of downpipes available to conduct a flow test. The products are a stock Mk7 GTI downpipe and a USP catted downpipe.
Each downpipe is connected to a flow bench using a straight silicone coupler hose. There is a bellmouth attached to the inlet end of the downpipe.
The flow bench is operated at a test depression of 28″ of H2O and the airflow at this pressure is recorded.
The USP downpipe has a reducer attachment at the outlet end to connect to the stock GTI exhaust.
The stock GTI downpipe is tested first and flows 224 CFM.
Next the USP Motorsports downpipe is tested, producing a reading of 450 CFM.
The results are compared in the following chart:
The USP Motorsport catted downpipe flows approximately double the airflow of the stock GTI downpipe at the test depression of 28″ of H2O.