Two things I think can really make the KX woods friendly. The 1st, I think most here would agree, the best change you can make is to add a flywheel weight. It really tames the "hit" and gives you a better spread of power (I have an 11 oz weight). The 2nd in my opinion, it to adjust gearing. (I dropped a tooth on the front sprocket, and went up one in the rear.)
I ride with a lot of quads. Its usually slow going, 1st-2nd gear most of the time. To make it easier on me, The bike is like a tractor. It can be lugged through the tight technical trails, but also is a blast to go hill climbing, it just keeps on going... Due to the gearing changes, I wish it had a 6 speed tranny, as I've lost some top speed, but I'll take the power at the bottom vs. top speed. I don't need to go 100 mph anymore, I'm to d**n old, and it takes a lot longer to heal when something goes wrong...
My son likes the changes so much, he's taken over my 250.
Another thought... Guys correct me if I'm wrong, (like that's never happened before) but I believe the FMF fatty pipe will also add to the bottom end.