I'm interested in getting performance gains from a catback on my 2017 Q50. However I'm not interested in making the car much louder. I was entertaining just doing the y pipe and mid pipe, leaving the OEM axle back. My hope is that the noise level would not increase much, and I'm also thinking the performance loss of leaving the OEM axle back would be minimal at the most. I'm curious if anybody else has done this or if anybody knows of a cat back that is pretty quiet. My biggest worry is droning, I cant stand that. Any help is greatly appreciated, thanks guys.