Originally Posted by JAM3S
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?