I can personally say this Tune is awesome! I saw huge improvement over stock and the car ran a lot more smoothly IMO. Here is a link to my review of the ESS Tune
I also can say Tom and the EAS crew are top notch. I recently stopped by there yesterday to get some things done to my M3 before turning it back in and his entire crew was very knowledgeable and respectful. I was very impressed with the whole place.
for those of you who are interested in a Tune the ESS Tune is a great way to go!