Dude, I ran the RPi GT for about 3 months then got the new GTM. With the GT the drone is only present from 1,600rpm to 2,000rpm. If you cruise on the highway at 75mph your rpm will be at 2,100rpm and you won't get any drone.
With the GTM exhaust, the drone isn't any louder, but there is a brand new drone range in addition to the drone range that was already present with the GT. The GTM also has a drone range from about 2,800 to 3,000rpm and it is higher pitched than the lower one, and it sounds SO good! Both drone ranges with the GT and the GTM make the F10 M5 come alive in my opinion. Without them, it sounds like you are just driving a BMW and not an ///M.
