Nice idea, and worth a try.
Its also true that every modification you buy for a car has an effect on how well it can drift... before I just thought suspension and tyres were the only thing that mattered.
For example adding more power might mean you can keep the tires spinning longer, but it also means that because acceleration force is higher there is more downforce on the back tyres, which means it might be harder to induce a slide or lose traction.
Also, I was surprised that doing some of the mission stuff (clutch, gear kits, flywheel, etc.) was making it harder to drift and that sometimes making a car more powerful can actually make a car MORE tractable.
The best way to find the ideal drift settings is just do small modifications at a time and go for a test drive after each one. Ive found the gtr only needs about 400 bhp (all engine mods but no turbo kits), doesnt need any mission mods, and drifts really well on stock suspension and tyres.