There was a thread on here about a month ago. There is a guy on here ( Brandon aka NoTalent) that works there. I have a ATK engine in my car with over five thousand miles on it and I'm very satisfied. I bought the 9000 series Scat crank with a set of their rods. I also put a set of the ATK aluminum heads made by Profiler with a healthy hydraulic roller. I bought mine as a long block and put my intake and fuel injection on it when it got here. I couldn't buy the parts for what the sold me the engine for. Brandon was great to talk to and work with.
I have not bought one yet because my plans are up in the air. But I have also talked to Brandon multiple times and he has always answered my questions and was willing to work with the plans I had. If I don't plan on using the 454 I have for my Malibu, I will be buying the 345hp 350 they sell.