Originally Posted by f32458
I can ask them on Monday.
Did you had the Eisenmann mufflers or the x pipe? I had the Akra Evo on the E90 and it droned badly from 1k ~ 3k and vibrated my rear windshield at cold start. ( maybe bad installation? ) The gains were very nice though.
Did your Eisenmann drone? Our cars drone even in stock platform at 1900 ~ 2100 rpm. Both E90 and E92 has the same minor issue imo. So there's no surprise if other aftermarket system has drone in the " ghetto " area. Did you felt any gains with your Eisenmann?
There was drone in the low rpm range but not too bad imo. There were no gains at all since it was just an axleback exhaust but great upgrade over stock.