Just installed Gibson Super Truck on a 4.6L 2002 Screw with the vibration dampener resinstalled. Is it abnormal for the engine to idle a little rough at a stop light? More specifically, it idles a little rough every time, between 600-700 rpm in the drive gear, overdrive on, and at a dead stop. Is this behavior a gas waster? I didn't have this problem with the stock system.

 

I have a Gibson Swept SIde and I have a rough Idle as well...I'm replacing it soon.

 

How bad is the idle? Is this cat-back fairly new

-Mike

 

I've had the cat back on for about a year, and it has idled rough ever since I put it on. I don't think there is enough back pressure and the engine is idling to low or something. I't not that bad of an idle I guess, but it pisses me off.

 

well, your're not alone, mine is doing the exact same thing, my idle rpm has dropped considerably which may be the cause of this mild rough idling.