Have Primera P10 1.6 Bj 95 Taking the gas away at approx.3500 Upm it bangs violently out of the exhaust. since I have fear for the kat steh the car for three days have asked a college what it can be,but he didn’t know anything either, Have Nissan dealer asked what it is. The dan Coputer connected the couldn’t find anything either. the nissan man has still seen the ignition,the kat looked up and renewed spark plugs (why was necessary). whether with old or new spark plugs he still bangs Needed quick help