The concept is devilishly simple: take a metal tube, weld it snugly into the end of your car's tailpipe so that the exhaust is forced through it, and presto -- you've converted your ride into a giant noisemaker. The sound emitted by whistle-tipped tailpipes is not quite a whistle. It's more like a high-pitched moan that evokes the sound of peeling rubber and mortally wounded wildebeest. During the past few months, these cacophonous contraptions have become the bane of residential neighborhoods throughout Oakland and Berkeley. Credit -- or blame -- for the unnecessary accessory reportedly lies with A-1 Muffler, Brake, and Radiators in Oakland, which popularized the devices. Oakland police are cracking down on the installations by enforcing laws against altering mufflers to create noise. Upset neighbors are hoping to see them banned, noting that in addition to being earsores, they encourage speeding (the whistling sound kicks in at around 30 mph; faster speeds generate more exhaust, which generates louder whistling). Maybe whistle-tips will eventually go the way of other automotive fads like fuzzy dashboards or air horns. In the meantime, local body shops are making an easy $100 for each whistler they install. And light sleepers are stocking up on earplugs.