User blog comment:UnknownGeneralHero/Aura in relation to physical prowess/@comment-5780397-20160217224728/@comment-5780397-20160218121716

Among many other things, you are assuming he did not train his body in the meanwhile, but in fact, he did, you can see Gon and Killua going to the gym and doing push-ups and running with Biscuit, which are only a couple of instances (another one would be that they scold the GI player for not training his body, implying they do it). Plus, he removed Illumi's needle, which gave him a huge boost in strength. And if you want to see the "realistic" side of it, he became a teen, so his body got stronger. Anyway, the last two are side arguments, but if you actually think about it, Killua at the beginning of the series really was just a child, it is natural that his strength would grow so much due to training, growth and removal of limits, simply because his body keeps growing with him for the two years he spent travelling. Anyway, the main point is that both he and Gon did indeed train their body, so it is impossible to calculate how much their strength increases thanks to aura alone.