After a couple of months of dealing with the MPE exhaust rattle, I finally found a permanent solution. I put the car on a lift and found the sleeve coupling (clamp band) between the mid-pipe and exhaust kept coming loose and rattling against the cross brace as mentioned in the very first post in this thread. No matter how hard I tightened it down, it was only a matter of time before it came loose again.
The solution is to get rid of the sleeve coupling and have a proper v-band flange installed. I found a
3" stainless steel v-band flange made by Vibrant Performance that worked perfectly for $75. There are less expensive versions out there which are aluminum, so make sure you pay attention and get the
stainless steel version to mate to your stainless steel exhaust pipe.
I looked around my area for a shop with a TIG welder who could do the work, and found a local hot rod fabricator called
Steel Farm Customs (SFC) who specialize in all kinds of custom builds working on everything from a Ferrari to an original 1932 hot rod - making my exhaust mod a walk in the park. TIG welders are harder to come by than MIG welders, and from
what I have read both can do the job but TIG is cleaner and more precise than MIG welding. Your choice.
The guys at SFC put the car on the lift and dropped the exhaust while leaving it on the car. The Vibrant v-band is 1" thick, so they cut exactly 1" off of the midpipe to make room. Next, they simply TIG welded each of the v-band flanges onto the midpipe and exhaust and put everything back together. It took just over an hour and cost about $100. It looks great and the rattle is 100% gone forever.