It's not so much that the Mopar OEM stuff is bad or anything, just that the electronics and coils we have available to us are more efficient and powerful than that of 40 or more years ago. (for the average car)
Of course racers had decent equipment back then but at what price for the average Joe.
HEI is simply one of the best running most efficient and powerful system out there as far as bang for the buck.
The title of the thread is "Best bang for the buck" and "better than stock" is what he requested.
That's HEI in a nutshell.