The welded Flowmaster somethings came off my 76 New Yorker the month I got the car.
Went with Walker Quiet something's. Very happy. No drown. Two cats, two mufflers now.
Power loss? Stock 440, heavy car, who knows.
love the car had a 1975 new yorker what a pleasure to cruise the highways and the 6 dead body trunk was perfect fit 5 pars of skis no problem , wish I still had the car , Even with the smog 440 it would move , not as well as my 70 pimperial but good