Dinan offers software, high flow intake and throttle body. I don't see the high flow intake on website, maybe the intake on the 4.8 is high flow, is not clear. If you couple that with a high flow exhaust you will have a significant gain. There are others that offer software also.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas