C-Kwik wrote:
I would not make such a general statement like this. I had my 80mm Greddy SP before I turbo'd. Fairly loud. Now I'm turbo'd and am running a straight pipe and it's a little louder. It really depends on a lot of things. Larger turbos tend to allow more sound to pass through. And it will also make a difference when and how much the wastegate opens.
I agree C-Kwik. A muffler is specifically designed for the purpose of using negative interference to cancel out sound. A turbo has such anti-noise properties; but they are incidental and not part of it's design, so it does not do as good of a job. A turbo also adds more metal to the exhaust which means more sound is absorbed by the mass of the tubing itself.
Regardless, I don't think trpower7 meant to say a turbo is quieter than a muffler -- only that you can get by without an exhaust on a turbo'd car.
On a related (and more humorous) story told to me by my father whilst drinking my first legal beers in a Candian bar: My dad and his friend discovered that they could make the friend's brother's truck backfire by turning the car off and the turning it back on again immediately. After a couple of times doing this, the car backfired a bit louder than usual. The end result of this was a muffler flying across the yard and into a small pond. The moral of the story? Uhhh . . . if your car backfires, don't put a $600 brand name exhaust on it.