03 yz 250 suspension

Completely depends on how much you weigh, how agressive you ride, where you ride.
If you bottom out add oil.
If you never bottom, remove oil or ride harder.
If it is to stiff, go with a lighter oil.
If it's to soft go with a heivier oil.
If your still concerned, go to the valve store then start all over again...

This should be in the suspension area, well because there is a suspension section and 2 strokes are not the only machines with suspension.

It would help to know your weight, type of riding, and ability, but the stock setup is not very good in my opinion.

The springs aren't too far off, but the valving reeks and they blow through the stroke way too easy.

For MX I'd try running the fluid level at 110mm from the top and see how that works. I believe the std level is ~130mm from the top (going from memory here).

fatmaxracing.com and I tried a LOT of setups on mine, and we got pretty good valving specs eventually. If you sent your forks to them, they could put in the right valving for you. It wasn't until I went to them for valving that the forks got really good.

We then converted the internals to a blend of KX-F and YZF parts with heavier springs, and it was even better yet. Now we've put Showa's on both ends, and I'm completely spoiled and will never go back to those old KYB's!

Compared to the '03 KYB's, yes the Showa's are tons better. But the '05 (and it sounds like especially '06) KYB twin chambers are much much improved.