An aftermarket intake will look different, and may result in more intake noise (air roar) but won't affect engine power output much if at all.

A tuning chip on the 4.4 has very limited impact. If you do get some more torque or hp at one point on the power curve, it is most likely very minor, and is a tradeoff for less torque or power at a slightly different point on the curve.

An exhaust isn't likely to add much power, perhaps a few hp, but it is easy to create very different exhaut notes, as described above.

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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