I have a friend who is running one behind a 460 in a scout. After we got everything figured out it was fine for a while. Then it started grinding they forgot to put a snap ring in it.
I believe they have the majority of their customer service stuff worked out. It was beyond bad when we were dealing with them.
It is a nice piece for sure. But like I say I was less than impressed by the customer service and the fact they assembled it wrong initially.
Pretty sure NWF problems involved the fact that the demand for their products was way more than they thought and so for a while things got sloppy.