Alrighty, before you run to the end of the leash I am aware that the Horizon series on X360 does not have true tuning like the Motorsports or FH2 (XB1). Now that we have that out of the way we can move forward. 
In FH I mainly just piddled with the game at first and lost interest due to other games. FH2 renewed my interest and I came back and did a 100% of it before FH2 was released. Since FH2 has come out I have already 100% completed it and gotten to Lvl 999 through SP and MP Modes. Now I am concentrating on buying cars I like (eventually all of them, but money is slow) and building them for various online aspects (Mainly Playground).
Now in FH2 I am very much enjoying myself and while there are aspects of FH that I miss and parts of FH2 (XB1) missing I am still a big fan of the game. However, I’d like to understand the Tuning (Upgrade) system a bit better.
I know generically many people say for example if you want a good drift car just pick a RWD w/ max upgrades and street tires, then have at it in Manual w/ Clutch. What I am trying to figure out is if the system that comes across as very straight forward and generic does in fact have more depth.
Like if I wanted to make a build that emphasized Drift, Drag, Street, Off-Road, Top Speed, Balanced, etc does the game allow for that level of difference. It’s like for instance you might not automatically jam a Race Transmission in every single car because the engine itself may not sync up correctly so the “extra/added” gears throw things a bit out of whack and you’d do better stopping at a Sport upgrade.
I’m also trying to figure out how to Approach the various Classes in order to optimize a car for best performance in A, B, C, D, etc so I feel more competitive in Playground for instance. I know it’s rare to not have S1 or S2 auto chosen by the masses, but one can hope.
Thanks for any enlightenment and discussion on this.