My 2017 GT350 has been the noisiest car I have ever owned. Last year I installed long tube headers, it was so high pitch that it was unbearable to rev up. On the street if you went over 3000 the sound was AAAAAAAAAAAAAHHHHHHHHHH. So I pulled exhaust and added a dual in and out x flow muffler by Magnaflow. Wow, it is really close to my 20 GT500 as far as sound, deeper, muffled somewhat. You can still tell it is a flat plane crank but very livable. Thought I would give ideas to those who maybe like me, hated the sound.