I've been reading that there is a new Dynomax VT muffler that really kills drone and retains HP at WOT. It may be a chore to fit them into a pantera exhaust system though. Barry http://www.network54.com/Forum/119419/message/1369099955/drone+fix http://www.network54.com/Forum/119419/message/1369603265/Drone+is+gone