Well, i think the E-test does give you an afr at 2000RPM or something but you're looking for consistancy during the RPM range. Get a dyno done. Dont worry about the chip, your car has knock sensors, it will retard the timing if need be.
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2002 TiAg M3 6mt
deoranged, dechromed, led tails, ZHP knob, UUC SS v3, GROM, OEM 220M 19's, Michelin Supersports
2006 YZF-R6, bunch of go-fast stuff