Hi, I have experience with power box from Stainbauer on my previous car Q7 3.0TDI.
For BMW 320d they offer:
http://www.steinbauer.cc/bg/products...35kw__3gq/b8Y/
The result was real! From 9 sec 0-100 originaly the Q7 goes to 8 sec 0-100 km/h.
Much better gear changes (6AT was the gearbox).
On 4th year, the power box was broken and after e-mail to the owner we received new one!
What about the warranty of car if you install additional tuning? Did you ask BMW? The AUDI installed the power box in their service 3 months after the purchase of car.
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equiped with: LCL3, 205, 2VF, 2VL, 3AG, 402, 420, 5DF, 494, 496, 610, 7AC, 710, ZP5, ZP9, ZPS