Let's assume for a moment that it gives the 1% power gain that they claim, at normal driving rpm. That means that at around 2000 rpm, you may need to drive at 2020 rpm to get the same power as before you installed it. Think you can notice that?

I'm with MD, pick your favourite charity and send them the money. Same effective performance difference, and you can feel better as well.

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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