034 Motorsports 3.5″ single exhaust system, 3″ mid-pipes with high-flow catalytic converters and dual magnaflow mufflers, was attached to the flowbench to get some idea of what kind of pressure losses a high performance aftermarket exhaust causes.
The first test was done on just the exhaust. A second test was run with 3″ downpipes attached to the exhaust. I use the Autospeed downpipes, I doubt there is any difference in flow characteristics of the ASP downpipes and other 3″ downpipe options.
With the downpipes attached:
For both tests some play-doh was attached to the edge of the pipe entrance to create a shape more like a bell-mouth. Prior test have shown that the sharp edge at the entrance can lower airflow slightly.
Until I can get around to testing a stock setup it will be difficult to assess these results. The pressure losses caused by this setup seem minimal.