Fins_UP, I have a TRD catback system and I too have the annoying drone that just drives me crazy sometimes. I decided to take it to a local exhaust shop to get some recommendations and he said that I currently have a 10" resonator on the TRD system and that they make 14" resonators that would possibly quiet it down enough to get rid of the drone. I can't be exactly sure, but it looked like it was a magnaflow catalog he was showing me with the resonator in it. I don't think they're vehicle specific, so any resonator in the right size should work. I'm going to put in an order for one with him and go back there to get it installed. We'll see how it turns out...