I've seen a bit of touge in the nikko area and up tsukuba san. Very hush hush, very well organized and of course people do it to compete against each other, not just for fun. Every time I've been to one someone had a small crash (coming down the mountain with the front bumper sticking out the back of your hachiroku is quite popular!). Most of the cars that participate are old mistreated bangers, old silvias, 86s, 180s, laurels, soarers, evo 1-3s, WRXs and a few rwd 32s. I guess I must have just seen the low budget side of touge, but to tell you the truth I haven't really heard of any more extreme machinery competing. Most also seem to prefer to drift rather than grip.