Your popping out the exhaust is either a lean condition and or exhaust leak. Most peeps are too cheep to install new crush gaskets when they R&R an exhaust. The exhaust has been removed at one point or it wouldn't be loud as they dont come that way from the factory.
Also, new stock parts known as take offs can be had cheap from peeps that have upgraded to aftermarket or performance parts. They do surface from time to time. (edited)