Like everyone else said, best bet is to get it on the dyno and see what your A/F numbers are. I'm in a similar boat as you, but with a Kenne Bell pushing about 12-13 lbs. I haven't had a chance to get it on the dyno yet, but in the mean time I've been taking it easy on the truck and I also richened the Predator tune the full 10%. Be careful that you change that parameter toward richer and pay no attention to the + and - symbols as they can confuse some people.
Justin
NHTOC#157 / 03 2-tone #9101
444 RWHP / 527 Ft-lbs TQ SAE