It's almost impossible for 2 cars to have the same exhaust system. Different manufacturer cats, headers, size piping, location of components, ect.
I don't know anything different but I had Magnaflow mini hi-flow cats welded directly into the inlet of ProChamber. After market hi-flow cats should not muffle the exhaust tone so much that it sounds stock, not at all.
*Stock headers, hi-flow cats, ProChamber, keep FM 44's- Should sound pretty tight!
Good Luck! Have Fun With It!!