Well, against the computer you don't have much of a chance at beating them on the take-off.
You should be doing time attack runs on Irohazaka a lot before taking on K.T. there. Remember to use as many jumps as possible to stay ahead, and gutter drop on the last few corners before the bridges.
I would also suggest using left foot braking on that course with the FD3S. It helped me out a lot in getting a boost out of corners.
As for shift points, Irohazaka is tricky as hell. The target gear is 4th on that course with an FD3S. You should brake and downshift to 3rd just as you turn into the corner, and upshift as soon as it hits redline when you exit the corner (it'll hit redline pretty fast). The only time you should shift to 5th is on the few long straights (I think there are two of them) and on the home stretch.
NEVER shift below 3rd, even after using a jump. The car will just over-rev and you'll lose more speed.
With these techniques, I can beat K.T. without him in my rearview at the end. Hope that all helped!
