The car does not shudder at all while backfiring. Only when shifting. The backfire noise is a muffled pop like sound coming from somewhere in the back of the car. Sometimes it is just one, sometimes a series of no more then three. It isn't a violent thing. My wife heard it while outside the car and she thought it sounded like it came from the midsection, not the tail end. Sometimes it sounds like it is on the right side, sometimes the left side. (when two happen, it sounds like that, one right, one left). It used to only happen after coming to a stop, but now it happens when accelerating as well. Sometimes it happens a lot, sometimes not at all during the day. But on most days it does backfire or make that noise at least once.

It is awful annoying though.

Ralph