looking at your "after" photos, i would say if you have a problem with your arms being a weak point, you address that in the tricep department...your bis definitely (appear to, in this photo, anyway) make up a disproportionate majority of your upper arm...i would imagine that if you hit the tris to a point where they "catch up" you'll be flirting with 16". BTW, they look damn closer to 15.5" and wouldn't pick them out as your weak point if i was asked to pick.