Those days RC racer run quick time by being very fast (but not precision driving, crash or off circuit is not uncommon). I also remember 石原 used to sell some limited edition OS 21 engine that are hand modified by him for about HKD$1000, which was tons of $$ then.
Compare with Masami, Masami is quick by being very very surgically precise in driving with almost zero mistake (but also with fast equipments), some of his 1/12 driving and 1987 2wd world championship drive were good textbook precision driving.
