ORIGINAL: mouthcaller
Why dont you call the guys at Indian Creek - they probably know more about their chokes and hevi-13 than all of us put together.
Steve Conover posts on the NTWF board as Night Hawk - He could also answer your ?.
Mouthcaller
Bingo! A friend of mine called them and asked about their chokes and Steve recommended the BDS .660 (I think that was the number) with the Hevi-13's and his pattern is as good as my Jelly Head / Nitro 4x5x7 pattern.