Re: how to get rid of the droning ?
I put on a 2-1/2" catback from Mustang on my
890 Lincoln Mark VII, just had to lengthen the pipes
a little in front of the mufflers, then had to reroute
around the bigger gas tank. I, too, have the drone,
mostly from 1500 to 2000 rpm.
It's caused by the pipes and the mufflers being the
same size, length, and the mufflers being in the same
position fore & aft on the pipes.
My stock exhaust had 2 diff length mufflers, and the
tail pipes were 1/8" diff size.
I put some of the new sound deadening material under
the back seat and under the rear carpet, and put
shields up over hte top of the mufflers. I made mine
out of sheet metal and fastened them on with long
U bolts to the pipes, but they are available commercially
check Summit, Jegs, etc.
It really helped, though I can still hear it a little.
I also changed rear gears to one deeper to get the
rpm up out of the drone zone for hiway driving.