I would love that and absolutely think it would add more action..

1. Winner takes a bigger purse... Say Mayweather vs Marquez was 60/40 split, Marquez win would make it 60/40 the other way.. Or Mayweather win would make it 70/30... OR, just have a set bonus that goes to the winner.

2. Additionally, a bonus for winning by knockout or TKO... I think this one would add huge excitement to boxing.. The only downside I would see is if someone was dominating a fight, think Winky vs Tito, Winky might fight a perfect fight, then in the last round or two just go for the KO, mixing up his winning recipe, and get himself KO'd by a lucky Tito punch..... That sort of thing would be a shame to see, purely for money's sake...
But I mean, there is nothing wrong with anyone who is dominating a fight trying to go for the knock out...

But seriously, I don't see why there isn't room for some sort of extra incentive for getting a favourable result in a fight..