I built a 3.5 inch cat back with a 3 inch catless downpipe all in my garage with pie cuts no bending. after about two weeks i had to order a resonator as the drone was awful. as it sits right now its a straight pipe with a vibrant 18" resonator and the drone is still there but not bad. it gives a amazing tone unlike any focus I've seen. if anyone else knows of a way to fully get rid of the drone it would be much appreciated.