Punishment:
Hwoarang can't launch DB3 and must settle for 40 damage. Due to pushback, he must use his WS44 to punish STC4 (which he should low parry) and his DF1-3 to punish STC1. As Hwo's i10 punish is only 17 damage, B1 is a better move than usual in this matchup.
Hwoarang B3 can make Feng's UF4 whiff at tip range. Feng's F4 is a more ideal punish. Feng can't exploit -14 moves here and only gets shoulder.
Back Kenpo
Less effective than usual in poke situations. At closer spacings Hwo LFF DF4 (his homing move) clips it, at very close spacings he can hit it with 1 jabs, and the second hit of his DF1-3 connects. It can also get clipped by random strings like 4444. Have a good idea of what Hwoarang will do when you use this. Alternatively, bait him using shallow hit DF1, where you can evade these options.
Before using in neutral, consider conditioning him to do less FF4 and WR moves. These tend to have good range. Kenpo easily makes his F1+2 whiff.
Kenpo is more useful if Hwoarang is in RFF. After RFS 2 puts him in RFF at +5, Kenpo can evade his homing DF3, his B2, his 2-B4, and other compelling options.
Poking:
Feng B4 stops Hwoarang's B2 and B1 easily without having to slow down his offense. If Hwoarang DF2 trades with DB3 he doesn't get his combo, but if F1+2 trades and he executes correctly, he does.
Non Kenpo Evasion:
After Hwoarang's D3-4, Feng BF1 evades the usual frame trap trio of RFS D4-3, RFS B3 and RFS DF4. If Hwo transitions back to LFS and uses D3-4 again, that will also be evaded and counterhit. Very few other characters can control this situation this way and Hwoarang is unlikely to expect it. This gets blown up by RFS UF4, Hwo's new hopkick. D3-4 to RFS jab or F4, or a delayed RDS DF4 can also blow this up.