If you bowl a lot of sport type conditions I'd opt for the NS2.  At the time the NS2 was one of the higher rated sport type condition balls out there.  I'd agree with that as I had a 15 lb'er when I used 15's.  It was a very good ball.

scotts33,

Thank you. Mainly bowl league. How would the Big Bang be polished?
Todd

The OG Big Bang in 15 lb. is 2.59 .038 and got more length and for medium conditions than the NS2 15 lb. 2.62 .048 designed for medium-heavy to heavy when it came out.  Both in OOB the Big Bang was Super Carbon cover and the NS2 Diamond cover.  I had both.   

Scotts33,

Thank you. I just got a NIB Yeah Baby. Very surprised at the strength. No Quit in this ball. I was thinking the Big Bang polished would be a good compliment to the YB? Or would the NS2 be better? Wanted to know how they compare RG and Diff #s sound close to the YB... Thank you

Those numbers I quoted are from their original.  if you don't use 15's and use 14 or 16 lb. they can vary a lot and need to be taken into account for correct layout and match up to bowlers stats. and lane conditions used on.  I used 15's back then now I use 14's which is one of the reasons I don't use LM/L/LF equipment anymore as their numbers for other weights are not on their site nor are they easy to get.  Good luck!