Ok, went ahead and got my 550i flashed with Dinan stage 1 (sorry Shiv, couldn't wait for you buddy). Results are impressive to say the least.
I would caution all of you coming from the 3 series (as I did) that the 550i is (and drives like) a huge car *curb weight is around 4,400lbs, and believe me you feel all of it*.
My 335 was far more "fun" to drive, but I'm trying to get back to driving *under* the speed limit
