Hello,

I installed the Magnaflow SISO 3" exhaust on my 2000 F150. After about a week, it developed a loud drone at about 1500-2000 rpm with the worst noise at 1800rpm. I checked and it is not leaking. Unfortunately, this rpm range translates to 55-65mph so it is especially loud on the highway going up hill at these speeds. It is most annoying at 65mph.

Anyway, I decided to re-mount the stock vibration dampener to see if it would help. I cut the old 2-1/2" clamp off flush with a band saw and welded on a new 3" clamp bracket. I had to also drill a new hole to match the 3" U bolt. I mounted the modified dampener about 1/2 way up the 3" pipe between the old tube and the muffler.

It certianly helped a lot with the droning noise. It is much less annoying now....

Thought you guys might want to know.....

 

I've had the same exhaust on for a couple months now and no problems with droning. But then we don't have too many hills here in Florida.

 

I've notice the same thing on mine, climbing hills it is really noticable. I had thought about reinstalling the damper, but didn't know if that would help. I think I will give it a try before I start towing the camper this year.