[kchummer]

yes, mine did it too shortly after magnaflow was installed....crawl under H2 about parallel to passenger side door, and right there where the two (exhaust) pipes connect is a metal band that needs tightened....use a 14mm socket (if I remember correctly) and tighten it down.....it will stop the annoying sound that is coming from the connection...when motor is cold and metal band is loose it causes this vibration at certain rpms (like at a take off), but once the pipes warm up it disappears...just tighten this clamp and it goes away!