...only if you had a whimpy cam and low compression. If you had a decent cam and decent compression, the Purple Hornies were more like a sound deadener that just knocked a few decibels off what would otherwise sound like open headers.
The cops in my hometown when I was a kid hated them!!! We regularly got noise tickets for running them on the street, but when you're running a 440 with 11.5 compression and a big Melling cam, or a hot 351 Cleveland like another one of my friends had, these header muffs will be LOUD!