Hi, So going through a bit of a mid life crisis I deleted the rear mufflers knowing it would cause terrible drone. (Have non resonated downpipes aswell). 1800 rpm, 30mph,70mph and under load it made me feel sick. Did a bit of research on j pipes and read about the calculation. Couldn't be bothered to do that, so bought two stainless 2" elbows and two extra baffled resonators got them welded to the rear sections and I can confirm I have 0% drone. I can't believe how well they have worked. I just wanted to share this because it's quite a cheap exhaust mod compared to a full exhaust systems out there.