[CobraEd]

I believe that the "need for some backpressure" is an old wives tail than stems from the need to richen the mixture if you open up the exhast. As an exagerated example to make the point: If you take a stock engine designed and jetted for a catalitic converter and single exhast and then put open headers on it, it will break up and misfire all over the place. But this is because given the new free flowing exhast, it will be jetted WAY too lean, not because there is no backpressure. So I think this is how the old wives tale got started. My Cobra has headers going right into the sidepipe with a 3" ID glasspack. From a flow perspective this is like open headers with a collector. When I switched to this configuration I had to richen up the jets to take full advantage of the enhanced flow out of the engine.

If you take that car used in the example that had the single exhast and richen up the jets, it will run great and develop way more power than it had before.

So there you have it, The world according to Ed.

Ed