Zoro said:
@ahill1 why do Yamcha/Krillin look so impressed by Goku defeating Chappa if they are above that level?
Well, it has more to do with @SIAD's points. All of the three were surprised with Goku's power after he defeated King Chappa, but Kuririn said something like "you shouldn't go all-out from the start" while laughing. This could imply Goku's power is a bit dangerous but still within a level he could win.
Kuririn looks more scared when Goku revealed he didn't use his full power against Chappa IMO. Even Kame-Sen'nin, who is far stronger than the power Goku used against Chappa, looks a bit surprised, saying this could be bad for him.
Besides, Kame-Sen'nin (already knowing Goku wasn't all-out against Chappa) said that all of the three had chances of winning the tournament, which would be a bit nonsense if Yamcha and Kuririn weren't at least a bit stronger than Goku (vs King Chappa) IMO.
Of course, there's also Yamcha saying he didn't think anybody could defeat Chapa-o that easily which could imply himself couldn't do it. This is a tough debate lol.