mufflers

MSHRED,
I think you are referring to our chart and yes, you are 100% correct. When we did the work, everything was consistent so that one company's data does not "blow more air" (mislead) about theirs. And it is very true, they all tend to use different values but the Walker one is one that works out about the best, 20.3" of water pressure and then measure the flow rate. Since we were able to use the same cars, on the same days, the same set-up, at the same track, the same calibrated gauges, and the same driving techniques, we were able to accurately compare.

Some manufacturers tend to ignore or downplay the air flow values. It is true, exhaust is not like smooth air, however, restrictive mufflers to a flow bench and on the car tend to restrict air from the engine and hence, tend to affect HP output negatively. That is why most chambered mufflers are not used for max performance. The Engine Masters Challenge guys quickly figured out that straight through mufflers gives the best power across the board. So do the FAST drivers. We saw it too with our tests.

Now if you hit chambered mufflers with air/exhaust right into the center of their Vee's, like center in center out mufflers do, they act differently but still not as good as straight through or those with smooth directors internally (like Areochambers).

Remember that on a 450 HP engine, the worst and best flowing HP mufflers make only about 10 HP peak between them so it comes down to more of sound preference if you are not worried about max performance. High HP engines are more sensitive. But, if you want max performance with minimal sound and minimal resonation, the chambered ones, based on all of our testing and published literature in many other instances, may not be the best ones to select.