exaust resonance

I have a tti 2.5inch exaust system hp manifolds turbo muflers and it has a rosonant noise around 2000 rpms that is 10 times louder than any outher rpm. Im assuming thats normall but i still dont like it.I think most of it is telescoping through the mid hanger. I was wondering if anybody had any luck nulling it and how they did it. Im thinking better floor insulation. is this realy normal for this system.