You do realize that there is a drivetrain loss somewhere between 20/25% which puts your HP figures 230/215HP. I am not sure if the dyno you used has to do with anything. So if there is a 25% drivetrain loss your at about 215HP which is close also depends on the milage on your engine.

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2006 BMW X5 (4.4i) N62

MY BMW X5... No matter how I disguise it... it's heritage keeps showing through!