This is how I would describe the race with the addition to a "drone" at about 1700 Rpm on deaccel only. Not unpleasant.
Looking forward to having them side by side to compare. I'm guessing very similar sound but race a few more decibels?
F10 30 Jahre M5/F80 30 Jahre M3
F82 M4 GTS
E36 M3 with S54 Swap/F22 M235 Dinan Stage 4
X15 X5 3.5i/03 Cooper S (Maxi Tuned +50bhp)
60 Impala (43k orig mi)