My friend has 00 JDM s2000 and
everytime he floor his car, he feels viberations at 6000rpm-9000rpm on 3rd,4th,5th gear.
In 1st and 2nd gear it is hard to notice. I think it is because rpm rises pretty fast.
The viberations feels like it is coming from engine or tranny.
So what is the problem?
Car has engine torque damper, I/H/E.

Sorry we DONT have Honda dealer in Korea..
We have to figure out ourself what is causing this problem.
Thank you!

 

The symptoms you describe are very similar to the reported bad CV joints.