So today I took out the silencer ring on my 04 5.9. I drove around for a bit and stoped at a drive through to get some dinner. I realized that my truck was shaking more than usual at idle. Once I got home I listened to the exhaust and noticed that it had a dip in the sound that was never there before. So I put the ring back in and the dip in the exhaust soud was still there. Can you guys explain this?