i have been on that mountain road- that one is awesome. here is a short video of the mx track they made in pyeongtech- about 10 min from Osan- it was fun:
they rented some bulldozers and a dump truck so they could change-up the track. luckly we were still able to ride on the other half. i actually started to get into it. Today was the first time i got both wheels off the ground on this track. was sure if the bike could handle it. but no bottom outs and a little hang time- not bad for a 300+lbs bike with 17T sprocket on front- lets just say i barely used second gear-lol kenda 270s are not the best choice if you want to actually ride agressive...or in the really wet/soft mud...