If your system is welded the only things I can suggest are renewing the rubber 'donut' hangers, changing their size (there are different diameters, changing the distance from the body), or examining your engine and sub frame mounts, perhaps they are worn causing the engine to sit different from how it should be. If the system is clamped you can change a lot more about how the pipes are orientated towards the body. Good luck, this can be an annoyance.