Today I had my exhaust installed by a shop. The only reason I let someone else do it was because I tried to take the downpipe bolts off with a ratchet and breaker bar with no luck. Since nobody close to me has an impact gun, I figured I'd let someone else deal with it. After they finished, I heard the truck from a distance and it sounded great. After I paid, I took off down the road and it ran really well, definite boost over the 3". When I got to a light and stopped, the truck started vibrating really bad and was really loud inside the cab. As soon as I touched the accelerator, it smoothed out nicely. I drove around for a while, and the idle never smoothed out. Is anybody familiar with this? I replaced a 3" straight pipe with a 4" Pinnacle Power system including muffler and it is much louder and rougher inside the cab at idle. I thought the addition of a muffler and larger diameter pipe would smooth it out. Do you think the guy screwed up the install somehow, or is this what I should've expected? Any help would be greatly appreciated.

 

make sure the pipe isn't hitting anywhere and vibrating against something

 

I just went and checked all clearances. It appears as though the downpipe is a **** hair away from the frame and is coming in contact with the insulation on the firewall slightly. Would that cause reverberation only at idle? Almost looks like if the downpipe could be turned slightly, it would clear everything as there is plenty of room on the other side of the pipe.

 

It turned out that was exactly the problem. Moved some things around down there and problem solved. I really appreciate having the combined knowledge of all of the people on this site. I have learned so much just in the past couple of months and hope to someday be the one giving advice and offering my expertise. By the way, the exhaust made a big difference and I love it, now that everything is in its proper place

 

always nice when you find a simple fix like that!