I have a year 2000 Felicia. Sometimes the exhaust resonates and knocks. Only happened s when people sat in back or weight in car. I had the exhaust mount rubber hangers renewed. This has helped a bit. Is there anything I can do to raise rear suspension or harden rear suspension so when passengers in back it doesn't sag too low? Exhaust resonates and knocks against rear axle beam.

I twisted my back box slightly and it cured it.

Got to move it so the over axle bend twists up higher.

Thanks Dan. I'll give that a try.

Also you could try bending the hangers on the exhaust, either that or find some stiffer rubber mountings, I got some polyurethane ones for mine which cured all my knocks.

And if the over-axle bend isn't directly over the axle you may be able to get a bit of front to back adjustment between the middle box and the cat. (Assuming the layout is similar to the diesel.)