KaganB

I had the same concerns. However I decided to go with it. I had timed my 520d from 80km/h to 180km/h before getting it chipped and it took around 28 sec. After the chip tuning the same acceleration took 17 seconds. That is some improvement. Considering a chipped 535d does the same acceleration around 12 seconds, 17 seconds is really good for a 2lt diesel. Before my tuning I could not even shake off a Honda Civic until 200km/h! Now I just leave most cars in the dust. Something to think about tuning boxes, I've been told chiptuning optimizes more parameters in the engine management system thus it is more efficient and better that those boxes. I would definitely go with the chip tuning. Mine cost 511 GBP at Superchips. My traction control light blinks even in third gear. Make sure the tuning guy wipes his fingerprints off your ECU box and does a clean job in the engine bay. We dont want the dealers to notice the change.

DJ2470

We have the same result with a "Poxer system" tuning box, without increase turbo charger pressure. The only difference is that, but you must know that increase turbo charger pressure more than 0,250 bars reduce life time of your turbo charger. Why take such risk if with tuning boxes you have the same result. A 520d tuning box cost 760? and in 5 minutes the car come back on original. Some people prefer tuning box, other chiptuning.