Just checked the specs on my wife's '04 e83 x3 6-speed manual. 3.64 final drives are used. Interesting. The ratios in the gear box are massaged as well. That would account for her X having a more "friendly" car-like driving attributes when it came to shifting. Her X also weighs about 500 lbs lighter at just over 4000 lbs. 1st gear is better and easier to live with, but still some what tall. Not sure how many e83 owners tow but it does have that option.

My guess, BMW is addressing the M54's lack of low end torque and 'rev' happy nature to move the weight around. Once you get 'er moving, the I6 power delivery is silky smooth with more urgency as the revs build. That is truly when the m54 is in its element and accounts for, at least in my mind, why they choose the gearing.

Sedc, I love the idea of an S54 powered e53. I know its been done, but I don't know much about it. The S54 would defiantly be a screamer, and would naturally have to be, to tap into its upper power reserves where that engine just thrives. If you go that far, you might tune it for a little more torque delivery down low. My guess is that you wouldn't give up anything that the M54 offered. Good Luck which ever direction you take, S/C'ed or whatever. Keep me posted.

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2005 X5 3.0, 6MT, Alpine White on Truffle Brown, Sport, Preim, and Cold Weather, Alpina Stainless Headers, AFe Intake, UUC SSK, OEM 87's, 3.64 Differential Swap,Performance Modified Euro 2 Tune, UUC LTW Flywheel and HD clutch, Bilstein B12 Suspension kit
Future mods ZHP/Schrick Cam Shaft upgrade, Operation code name:Doppelschrauben-Kompressor

Wife's Ride: 2011 e70 X5 351 M///Sport.

Also in the fold: 2004 X3 3.0, 6MT, Black Sapphire on Terracotta, port, Premium, Cold Weather.