What is SPL? "Sound Pressure Level"? Of the cooling fan?
yes, there are limits to how much heat can be removed by a dual-slot blower without making it extremely loud. open coolers can do a bit better, with the trade-off that they dump most of the heat inside your chassis rather than out the back.
the bigger issue is where all that additional heat is going and how. I'll be paying close attention to the SPL metrics for this generation.