I'd like to point out that in our chart, when you see StraightLine Performance, those are Magnaflow mufflers.

Another very important point is that the mufflers we tested (those with chambers and "V"s inside them), were offset in and offset out or center out. The first jog the exhaust gas has to take to get into those mufflers really affects its flow. And it should as the exhaust gas pretty much hits a flat surface as it first enters into the muffler.

All the cars we tested them on acted the same way, performance dropped compared to straight through or center in mufflers. Center in versions of chambered mufflers work much better although the sound level did not change much. Hooker Aerochambers, when offset in (are made differently) flowed better and ran better than some others.

We tested other mufflers but chose not to share them in this chart since we were doing mufflers that typically are used on street cars. At the time, very few cars used center in and center out rectangular or oval mufflers so we did not publish results.

We learned that overall, it was pretty simple: when the air can get in and out smoothly, the power level seemed to stay higher. When the mufflers had sound "absorbing" materials in them (more so than only stainless steel) they were quieter. So, combine a good perforated tube pattern, high flow potential, and good sound "absorbing" material and you get sound control, nice sound, and better performance. In other words, you get a muffler that truly muffles and ones that let the engine run well and the car perform at the strip. If you need more sound or roar or rumbling, it is often a tradeoff with power output but, in life, it's all a tradeoff anyway right? :):)

Tom Hand