There seems to be some people who know quite a bit about Xia Ke Xin here, so let me bring up something to think about. It's often accepted that Zhang San and Li Si are a notch above the martial arts level of the best Central Plain warriors, namely Bai Zizai, Xie Yanke, Abbot Miaodi and Priest Yucha. However, I have not been able to find any solid proof to support this theory. I hereby explain my doubts.
In chpt 1, Xie Yanke forced the swords out of several Snow Mountain disciples with 10% of his power. Later, Zhang San also de-weaponed several Snow Mountain disciples, albeit these guys were much higher in senority compared to the fellows Xie subdued. But Xie only used a small portion of his strength, so I think the feats may be comparable.
when SPT and Bai Zizai met, it was obvious SPT's internal energy is light years above Bai. But this is after a boost on SPT's part from Zhang San and Li Si's poisonous drinks. Prior to the drinks, SPT also had a lot more Internal energy than Zhang or Li; who knows how the big of a discrepency after the drinks. So perhaps Zhang and Li are comparable to Bai.
I hope to hear your opinion regarding this topic.