So I've been emailing them tons of question this week and so far they have been nothing but fast and extremely helpful. I purchased the Stage 1 tune to give them a try. They required me to list all my customization I've done to my S4 before they build the tune file which I find very cool. No longer will I be running a one size fits all tune but one that optimized to my S4. I should be getting a cable and software this week to load the tune. Once that is done we start collecting logs so that the tune can be optimized even more. It is nearly the same process of doing custom tune at your local tuner minus the dyno. They offer multi-tune option if I want to switch from 91 to 93 oct, which is similar to the APR. I'll properly upgrade to that if all goes well. What I'm most impressed with, is that I can upgrade to there next stage and it only cost $40, but I would need to upgrade my fuel injectors. All in all, I'm pretty excited about this and look forward to "feeling" the results. I'll post a full review later this month once everything is installed and optimized.