Hi,
I made 2 videos where I show what I upgrade and how I tune my Supra and my S13. The S13 is really for low horsepower Tandem and the Supra can be enjoyed on public lobbies.
Supra : Forza 6 / Toyota Supra Drift Build with Tune - YouTube
S13 : Forza 6 / Nissan S13 Drift Build with Tune - YouTube
These can be used as start for further modification to suit your needs.
Thanks