I don't really get into it...
Of course its cool and all, its just the tiny margin for error puts me off ever wanting to do it.
I don't know much about Hashiriya Touge, but Touge itself comes in many forms: driving, downhill bike riding, walking, joggging... anything really that involves going up or down a mountain. If you look at the Kanji for "Touge", it actually consists of three seperate Kanjis joined together 1) Yama (mountain) 2) ue (up) and 3) shita (down).
That aside, I do know that alot of the Touge Drift is def underground and not really presented in a way that could inform the police of their activities (websites etc). I live REALLY close to Mt Rokko where they have Touge going on, yet I've only been out there once and our arrival signaled the end of the fun for some reason! It seemed pretty organised, and the cars go off in pairs trying to overtake each other before they get to the end of the predetermined distance or marker or something. I never met the guy who took us out there again, so thats why I haven't been since.
I tried looking on the 'net for more info, but nothing really to answer the questions posted by Intensevil. Sorry!