silversho is correct in his method to eliminate drone. My solution is the same. I have a 2011 Mustang GT that was used as the test mule for
solo-performance exhaust. I spent 4 days in Hamilton Ontario Canada. There they made jigs from my car for the 11-14 GT's. The nice thing about their system is the "J" pipe is adjustable so it can be tailored to work with any car. All cars dont drone at the same rpm. I've had it on my car for 3 years and it totally eliminated the drone and it sounds pretty incredible. They have been in business for 50 yrs or more so they know exhaust.. I've mentioned before that I was going to contact Jeff at Solo and see if he could make a custom system for my SHO. I'm going to be waiting till spring but if anybody is interested they could contact Solo and ask if they are going to enter the SHO arena. That is their signature exhaust solution to fix drone. Check out their web site to see the layout of their pipes. worth the visit to see how it's done for a business. Check out any of their performance kits, doesn't matter really cause their basically the same only different to fit each car. I am
going to pursue their system whether they become kits or its a total custom.
https://solo-performance.com/performance-exhaust-system