No overview required. Just follow fred's link:
http://justkdx.dirtrider.net
BOOKMARK it. Read the whole thing.
Jetting. Carb tuning (and jetting). Step by step hop ups (and jetting). Kickstart upgrade (and jetting). RB carb info (and jetting).
You may get the idea that
JETTING is critical. That's cuz it is. The single bestest thing you can do for this bike, your next bike, and every other bike.
Guess that's an overview, huh?
BTW..the term 'gnarly' doesn't mean anything. FmF makes two pipes for the H model kdx...a -30 (rev) and the -35 (torque). All the descriptive terms used, gnarly, burly, desert, gold, ...they don't do anything but confuse the issue. To top it off, some catalogs call the same pipe different things!!
For the 200 AND the 220...both pipes fit, both do the same thing. Again.. the -30 is the rev (tuned for the top), the -35 is the torque (tuned for the bottom). If you ride tight stuff (3rd gear and below) the torque is for you. If you're in 4-6 most of the time the rev is for you.
Buy 'em both! Change 'em as suits you.
It works for me!!! ;)