I cut my resonator out and replaced with straight pipes and I don't have any noticeable difference in cabin noise. When the front windows are down I can deffinitely hear more a growl though. I like the straight pipes because its not overwhelming like a B&B TriFlow or an Eisenmann...its more subtle. I had a TriFlow on my old M3 and even though I loved it, it was a bit obnoxious. At least once a week I had random people off the street telling to take my car in for service because the exhaust must be broken...that's when I would jump in the car rev her up a little and blow them across the street :-)