Isn't it reasonable to think that the F40 is NOT stock in this race?
Do you mean the Best Motoring team intentionally modified the F40 to make it win the race ? I don't think so, and in that race BM placed the F40 at the back of the grid as it has the best power/weight ratio ( BM lined the grid based on power/weight ratio ) I just checked my BM video collection, the F40 was featured in BM race at Tsukuba at least 3 times, 1992, 1994 and 1996. One of them also had quarter mile, top speed battle, dyno runs and wet skid pad on all of the cars. The F40 also had technical interview regarding the suspension, factory tires, brake pedal pressure and touge driving.
For the race above, it's from 1992 Super Battle, the BM video features high speed 150kmh-0 braking while turning test on damp surface, Yatabe oval test track ( quarter mile, top speed and lap time ), dyno run ( BOSCH chassis dyno courtesy of Veilside ), Touge test, and wet skidpad. The F40 had 530 PS and CTR 518 PS from the BOSCH chassis/wheel dyno, and from the top speed+quarter mile time recorded, these cars are still inline within stock performance limit. For top speed, the F40 posted 282.36 kmh while CTR beats it by a hair by posting 285.71 kmh. For quarter mile, I made a mistake and edited my previous post, the CTR beaten the F40 by posting 12.531s against F40 12.998s. These figures are from the cars in the race video I posted. The CTR was noted for having better launch traction than F40 during the standing quarter mile at Yatabe, the CTR also noted running very high tire pressure at Yatabe as it was pushed to the limit for top speed.
For basic specs, the CTR had 518PS/1400kg weight with 47/63 distribution, while the F40 packs 530PS, tips the scale at 1210kg with 39/61 distribution, I'd say CTR did pretty well for it's power/weight ratio.