Mine don't have that sound nearly as badly. Really, I only hear the "header sound" when I'm ******* the throttle and if I'm listening for it specifically. The normal growl from the exhaust masks it. When cruising, I just hear the mild rumble from the rest of the exhaust, emanating from behind and not at the firewall. They're coated inside and out but also a tri-Y design, and I guess that breaks up the sound so the pinging and airy sound in the collectors is minimalized. I also don't have cats. If I did, I wouldn't need 40" of mufflers to bring it to a comfortable sound level.