Here’s a video of a news story about some whistling things you can have on your exhaust pipe. No word on whether they are tunable.
http://homepage.mac.com/howheels/rubpics/woowoo.wmv</a](http://homepage.mac.com/howheels/rubpics/woowoo.wmv">http://homepage.mac.com/howheels/rubpics/woowoo.wmv</a)>
