As a relative beginner, I think you should pick up the premium S13 Silvia (Silvia K's Dia Selection (S13) '90), change the oil, slap on some comfort hard tires, disable ABS, and head into your own lounge to get a feel for how the car behaves in this state. Dial down the brake balance a little bit because the default differential won't make 5/5 easy, and maybe upgrade the clutch to make up for the power deficiency. Learn braking points for tracks you're likely to gravitate towards and try to slide the car using its weight instead of horsepower. Get a feel for the car, and then buy the close-ratio 6-speed and mid-rpm turbo kit for a slight bump in the wheelspin. Finally you can look on here for tunes for that particular car, I used one and adjusted it slightly, and I really benefited from learning with the unmodified car.