From what I have read is that the Stage 1 is the remaps. Stage 3 is strictly for the mapping of the throttle body. There were some horror stories of people buying the Dinan throttle body and having a different tune (not Dinan) and it messing with the maps. It surprises me that a throttle body would make that much of a difference.

Also when I was looking for info a while back, it does not seem like there is really any real horsepower gain out of it. Most of the threads I read were from 3 series and they were saying 1-2hp. I know its a different engine entirely, but I don't think it will be much more. I'm sure there are threads out there for the N62 whether it be here or on the interwebs... when I was looking up on it I was looking on the M54.

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05 X5 3.0i - Gone Sport/Cold Weather/Summer/Premium... My Mutt
Toledo Blue, Nav (non DSP), AFE Dry Panel, H&R 30mm rear spacers
Now '10 535i ///M-Sport
RB PCV • Mishimoto OCC • BMS DCI • ER CP • MHD Stage 1 93