The 4WD wouldn't do you any good on an autocross course. As a matter of fact, it'd only be to your disadvantage due to the extra weight it adds.
I've autocrossed my Justy now for a full season and I wouldn't advise it to anybody who wanted to win. It's been a great deal of fun, but the poor thing is just totally outclassed by so many other cars in its class. H-Stock is seeing a great deal of interest lately with all kinds of new sporty economy cars coming to market and the Justy simply can't hack it.
Of course there's always the possibility that I suck. I don't think I do, but it's possible. Still, compare it to non-turbo Eclipses and new Minis. Really, it's just not even close.
Fun, but not close.
Now, if you wanted to race it in FSP or something, that'd be a hell of a lot of fun. Turbo it or something for a mod class. Yeah...