'78 Arctic Cat Jag 340. Motor runs and everything seems fine except the last time went to run it and it seemed to vibrate a lot and then the muffler popped off. I later installed new springs to hold the y-pipe and muffler together but when I give is a lot of throttle you can see the muffler and y-pipe come appart. Now the flanges on them are messed up a little but I think I can straigten them up. What would cause this???? A bad muffler???? How do I find out what's going on??????