I want to buy and mod a car over time to 400WHP+....... Is300, Mazdaspeed6, Genesis 2.0T/3.8 if they come out with turbo kit, 330i if good kit comes out, G35, Audi A4 3.0/3.2 if turbo kit becomes available, audi A3 3.2 if turbo kit comes available....... Which one would be the Cheapest to mod...