I am not an audio guy so my audio opinion is weak but the Hi-Fi or Premium is much better. I am sure other diagree but I think it make a big difference. As for the Seats, I would not get a BMW without the multi-countour seats. They have much more adjustability than the sport seats and are 100x better than the basic stock seats. If I could only have 1, the seats would be the choice.

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2012 X5 50i ZAP(2VA, 336, 465), ZTP, ZPP, ZPS(6VC), ZCW, ZRC, 322, 4UB, 4NC, 610
2011 ///M3 Silverstone II
2011 X5 50i(lemon)
-- SOLD --
08 550 Msport
07 X5 4.8I sport
04 545i sport
02 4.4i sport
01 540I M/sport
00 SL500
97 SL500