I got a Sprint Booster for my E60 545i last year and I just love it. So when we got our E70 X5 3.0i almost two months ago for my wife we were both disappointed that the 3.0 seemed to accelerate slower than her old E53 X5 3.0. So last week I took the Sprint Booster out of my 545 and installed it in her E70 and it made a very noticeable difference in acceleration. So I'm going to leave than one in her E70 and buy another one for my 545.
I am almost certain that the Sprint Booster from your MB will not fit the E70 as the connector would almost certainly be different (even if the actual circuitry was the same). The part numbers for the BMW and MB versions are different too.

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rodybmw