H&S is extremely popular for the 6.4 powerstroke and 6.7 cummins. Their 6.0L tuning is very new, like only been out for a couple months. I had the chance to test a mini-maxx but didn't take the opportunity, wish I would have! Its going to be hard to find someone with an H&S for a while mostly because SCT tuners are so popular.
I will tell you I put a Mini-Maxx on my fathers 6.4 powerstroke and have done 2 XRT tuners on 6.7 Cummins and everyone of those trucks runs awesome! I have been very impressed with their tuning for being such a new company.