I tried searching, but just can't find the keywords; I recently had a true dual conversion done. We hooked the x-pipe into the right/left side rubber hangers that the original driver side was hooked into. We were concerned it may knock around because the rubber material looked pretty stretched, but left it that way. When going over bumpy surfaces (Happens more on singular bumps, like speedbumps or potholes where the body will travel up/down), I've been getting a knock that felt like it was coming from under my seat/mid-car. I think I remember it being said that newer models (I have an 07) don't have these brackets. Is this a common occurrence, hence the removal of these in later models? Should I cut the hangers and will the pipe suspend itself safely/reliably?

You guys are the best with info. Thanks

 

Time to put her up on the ramps and physically "agitate" the exhaust system. If it was coming from the rear I'd suggest checking if the rear brackets were tapping the frame.

 

Check for drive shaft clearances when the rear suspension is not under load.
You might see stuff like this...

 

Cut the hanger rods near the x-pipe off. They're an assembly line aid that Ford itself suggests removing in a TSB

 

Check the clearance around the rear end. My pipes were slapping one of the supports for the rear end. try slightly turning the pipes and see if it goes away. Also, check the hangers on the mufflers and make sure they aren't coming in contact with the bumper support or the hangers that attach to the frame. My pypes kit need the driver side hanger shortened slightly and some cushion between the bend in the muffler hanger and the rubber hanger on the frame.