I did,I just swapped engines in my bird.I had a 455 with the X pipe and had a bad drone at 2000.Pulled it and put in a H and it went away.Fast forward to now.I took the 455 out,put in a 428 RA V with a much bigger cam and the same H pipe system is now 86 decibels at 2000!I have the 14 in 2 1/2 super turbos.I called my shop friday to talk to him about new mufflers.I almost went back to my 18in Hushpowers but I want something more quiet like maybe what came on HiPo factory RA IV cars.I drive my cars too much to live with that kind of noise level.Tom

Hi Tom, rumors out that you cut out X pipes from exhaust on Pontiacs and removed drone? My Pypes with X pipe sucks. I hate it drone no matter what muffler.