I am well aware of my own limfacs as driver as well,
however, two things I noticed, even given my lack of experience.
Wheel spin coming up out of the boot --:> fix=LSD
brakes got a bit softer later in the session on sunday (was wet out) --> fix= at least upgraded pads.
N57 with tri-turbo from M550d (ok, j/k)
FS:Sub Amp - works w/ Technic harness! MRD-M300 - cheap