I've had my 99 F150 for 11 months now. In spring I had a Flowmaster cat back system installed. The shop did not weld it. When I hit a bump in the road, I can hear a rattling type of sound coming for underneath the truck.
Every time I've had the truck in for any type of work or an oil change, I've had them look under the truck for anything that could be making this noise. So could the exhaust be making the noise since it is not welded? I thought about it today and I don't recall any noise like this befor I had the exhaust put on. It does sound like metal on metal.
Hmmm, should I have just went with the Borla?
Thanks guys, Eric

 

I can't believe the shop didn't weld it when they installed it.....pure laziness! Definitely have it welded together unless you don't like the sound, then buy a new muffler and then weld it.

John

 

if the shop did a rough handed job while taking the old system off they might have shaken the internals of one of the cats loose. I see it all the time!

lets hope its not that!

good luck-

 

I sure hope it's not the cats. I think I will call the shop that did the work and see what they will do. Thanks guys. Eric