Holy Carbon... on the list?
What a total douche. OCUK Motors meet on his front lawn with burnouts and donuts till he comes out with the paperwork?
How on earth is it that the M cars are ITB's and just work. I was under the impression its near to impossible to get ITB's to work reliably in varying weather... I know its just probably because when I considered it (ITB's on the S2k) its aftermarket and thus more difficult, but I was in genuine shock when Pete told me his e39 M5 had ITB's.... bloody bmw genius strikes again
The ITBs on the M cars are all still 'fed' air by a conventional style intake plenum, which through its shape influences the flow to each cylinder and effectively lengthens the inlet tract. With the aftermarket style 'open' ITBs you don't benefit from this and thus they can behave less predictably (a plenum can be used to help manage fairly equal minimum flow/pressure across most common operating temps at low revs, with nothing more than open ram pipes on the bodies and a filter you don't get this so more complex manual tuning of each throttle body can be necessary).
The BMW engines have the advantage that they are designed for the ITBs from the off too, which would influence things like cylinder head design, cam profiles, injector positioning, and the ecu. If you are designing an engine from the off to have ITBs you can optimise everything a lot more than you'd ever achieve with aftermarket bolt ons.