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      11-26-2020, 07:32 PM   #30
LongBeachDinanFan
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Drives: M3
Join Date: Jan 2015
Location: LB, CA

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Quote:
Originally Posted by greentrbo95gst View Post
I just picked up my 21 M5 comp yesterday and I have been trying to decide between BM3 and JB4, but hard to find good opinions these days. I even asked several vendors on this board with no response.
Are you guys able to tell me major differences between these two and main things I should be concerned with? Thanks
BM3 is a flash tune that changes tables in the ECU, JB4 is a piggyback system that plugs in to sensors in the engine bay and changes the tuning that way. They have a FAQ that answers most of the basic questions but the bottom line is flash tuning can make a little more power but then you void your warranty/lease, meanwhile JB4 can be a little more of a headache but it can be removed without a trace when needed.
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