Dang, MeTaL=DeaTh, but your member-name is a toughie to type!!!Anyway, similar to your point, my experience is somewhat limited. However, did some poking around on the \'net for an answer. Wouldn\'t have taken the time to post on this point except that I had a hopped up Honda (I\'ll describe as "full-blown Gran Tourismo looking" -- how\'s that!?) pass me today on the interstate with a simple personalized license plate that read "J-SPEC".
With my curiosity peaked by the guy\'s plate and Deadly Hampster\'s question posed, I decided to do some searching and basically MeTal=DeaTh is correct. I\'d go one further by my investigation and say that "A-spec" refers to American cars that are "supposed to be" modified to specific specifications. The idea is that everyone is on a same (albeit high-performance) playing field and that what is left over is simply driver\'s skill that wins the race.
I would therefore deduce that "J-spec" refers to Japanese cars under similar conditions for race competition.
Anyway, now I know why the Honda had the "J-SPEC" plate!
-w1ngman