the exhaust mount rubbers fatigue with age,, the mounting points need one particular consideration above all aesthetics. That is - that the flexible is true, without kinks or s bend misalignment.
To achieve that may mean modification or adaption of the " new" verses the " old" and yes its a long process.. there is no easy one stop,end all solution. it requires on to fit the exhaust based solely on ones own experience, and observation of reaction to change,, it really is its own thing... not one anyone can can say.. " do this" because there is no " do this" just pointer replies.
and getting the exhaust outlet pipes true in the flexible joint and true in the bumper is not something anyone can tell you how.. not me... at least...
its yours.. fix it.. if you cant pay someone to fix it for you.. its your choice.