Buy the HKS time attack evo and don't upgrade it.
Do the Fujimo full course reverse and rewind on every corner so you're getting about 900-1500. You will be able to get 3000+ on some.
You don't need to be going fast just close to the corner to get a good score.
On some straights you'll see the line bend in the middle, there you can drift and get an extra 600.
Repeat, rinse repeate that's how I did it