Gonstead wrote:
Get Yamcha going all bandit on Birusu and stabbing him in the back when he's not paying attention.
Or... it's revealed he's actually a Saiyan and goes Super *cue Vegeta giving up, leaving Earth and never coming back* XD.
As for the falling out, what if his Family and Friends abandoned him due to his selfish desires and he was actually hurt by it *Cue a big teary scene with Goku exclaiming "What have I done!?"*.
Vegeta: ...I don't want to live on this planet anymore.
He doesn't even go SSJ, just to make Vegeta's pride be destroyed, pure human god killing.
All you gotta do is take this speech, drop a line or two, and throw a "Wolf Fang Fist" at the end, and you've got Yamucha's one awesome victory:
http://www.youtube.com/watch?v=1Wc--lwc3XM#t=6m48s
"Even if Mankind is stupid and doomed to be destroyed by the Gods, only one blow will be enough for me. I'm going to pierce his body with my fist! This shall be proof that mankind lived on this Earth! BURN TO YOUR HIGHEST LIMIT, MY KI! *insert Wolf Fang Fist here*"
...Yeah, probably too badass for Yamucha.
Goku not seeing everyone for years since it took that long for them to forgive him? That's actually an interesting concept with a lot of emotion behind it...Somehow, I picture Toriyama not going that route though.
As for Yamucha stealing his weapon...that's actually not half bad an idea to call back to his bandit routes (insert "Toriyama barely remembers Yamucha as is, much less that he was a bandit" here).