I'm gonna swing the other way here.
Having owned the outlaw140 for about 2 years i can't say i'm looking for more power on it.
Geared to hit 100k's at top of 4th, i wouldn't want to go a lot faster than that on a china bike haha.
A mate of mine has the 160 and yeah, power wheelies instead of clutch wheelies, it has a lot of power, but you're on a pitty and unless you're riding in a very boring area, engine displacement won't be what you will be wanting more of, wheel sizemaybe but that's half the fun.
What i'd do:
With the money for the 160, buy the 140, a tube of loctite, a fat kenda rear tyre, new engine oil, air filter oil, fork oil and protaper bars if it doesn't come with them.