There are a few cosmetic and functional changes that can be coded, such as lights, locking, and so on. You can get the speed limiter and rev limiter changed, but are those really performance upgrades? Naturally aspirated engines don't make appreciably more hp with just coding.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue