A very worthwhile investment, especially if you have a tune. See comments in this thread:
http://www.e90post.com/forums/showth...&highlight=GFB
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PTF Map, Pure Turbo Stage 1, GFB DV+, Mfactory LSD, AA FMIC, B12 Pro Kit, M3 FCA, AR DP and
Dynavin N6, Mosconi AS100.4, AS100.4, AS200.2, Micro Precision tweeters & woofers, Esotar2 1200