[CWizard]

Are you sure it's the size of the sidepipe opening and not just the result of engine movement bouncing the pipe off the bottom of the hole? If the pipe has insufficient clearance from the bottom of the pass side hole AND you have soft motor mounts, this could be the problem. (Been there...). Fix with polyurethane motor mounts (as someone suggested above) and make sure you have at least 3/4" between the pipe and bottom of the hole. Good luck.