most folks love it. its definitely the cheapest, easiest, most warranty-friendly mod you'll ever see when it comes to time + money in vs. power out.
There are downsides (if you're looking for them). You will not want the dealer to know you have it. you will want to purchase the cable to remove shadow codes. As it is a piggy-back and not a true retune, it is not technically as high-quality a way to tune the car as-say-the RennTech tune for example. Added power does mean faster degradation, but no one has found any signs of premature failure due to the JBD of which I am aware.
2011 e90 335d
2007 e70 x5 4.8i
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