$250 split second turbo tuner, a simple plug in module that gives the N54 40 hp and 50 ft. lbs of torque. This has to be one of the easiest and most reliable upgrades you can do. It has been so effective, when I purchased by 335i the dealership in Jacksonville was offering this upgrade, but at a much higher price of course. Instructions can be found almost everywhere, google or Bavarian Autosport, maybe even Turner. I recommend using a USB cable; I was able to take it off and on without any issues using one of these types of cables. Immediate seat of the pants improvement just by plugging this in. Any questions? Contact me. Thanks.
