Tuner at heart!

I still cannot describe how much I evolved into the tuning aspects just because of the dullness of occidental car culture. I've grown with the wild visuals of the 1990s and 2000s, the restorations and mods in the 2010s, but I can understand that looks can go along pretty well with quality from the 2020s onwards. Market niches will continue existing, but if you want a car that look deceivingly regular but show its amazing performance on the curves, I can give you a little glimpse into my tuner heart. I will use the Nissan Silvia/Gazelle (RPS13) as a demonstration.

Tires
Usually you should go easy with them. Since I feel the need to go over holes, bumps, ramps and sidewalk, I really consider a middle ground between soft and hard. I really don't feel confortable using superbly wide tires if the power doesn't match the purpose. I wouldn't go past a 215 mm width, 55 mm height on sidewall, on a very mild 14 or 15 inch set of alloy wheels. I guess the 205 mm will feel already kinda big enough for such anything european, american or asian sport compact class of car.

Wheels
I tend to respect the original measure. The RPS13 generation came with the basic 14 inches, but 15 is a nice middle and my absolute limit is 16 inches. I've seen a plenty of cars with large factory wheels around 16, 17 and 18 inch wheels and I really dislike very tall wheels for two things: (a) they require a lot more effort from the drivetrain to move and stop, and (b) they tend to weigh so much more in comparison with a smaller set. As much as we have carbon fiber wheels nowadays, I really wouldn't like try my luck on the beyond a very flat race track. Smaller wheels will always spin more, faster and be easier to stop with nice brakes.

Brakes
The stock four-wheel-discs setup is enough on a car that weighs around 1100 kg. Vented? Perfect! I really think 4 pots front and 2 pot rear might be enough to last a lifetime. Competition fluid and you really don't need that much beyond it. Ok, maybe a 2 pot in the rear if you really enjoy slamming on a braking point into a perfect zero-counter on the curves. Good pads won't burn beyond the necessary.

Suspension
Adjustable coil overs. But as long as just double the load of shocks and springs based on values from the stock settings, it won't ruin your experience. Camber angle? Zero! Toe angle? Zero! With this alignment you can drive through most obstacles immune to adversities. Believe-me, even the professional drivers and the teams realize that about -2° to -5° (negative degrees) is enough. And in daily tuner life, you really don't want anything beyond the absolute 0°! Again, only for track purposes and that will depend a lot on other factors. And, the height of the car should not be lower than 50% of the stock height of the car. Silvia/Gazelle S13 were 1.30 m tall, and just by lowering to 1.15 cm is enough to not rip off things below your butt.

Flywheel
A balanced lightweight one, if you really want to enjoy the early response of the engine. Either a racing one or drilling the stock one.

Gearbox
The original box will be enough for a lifetime. You probably carve for a 6-speed manual from the S15 generation, but that's only if you're really into saving fuel in traffic (especially in highways) and spending more of your lifetime on the circuits. Cool to keep shifting since many Civic popularized the 6-speed box on the SI and Type-R versions, but the old 5-speed is already enough. They are the same for S13, S14 and S15 so... doesn't matter that much. Automatics? Never. They're very hard to be pushed to the limits, even by professionals and are mostly annoying when you really want to drive entirely by yourself. Manuals are forever.

Driveshaft
You can probably save a lot of money since the stock iron one will last an eternity. I'd recommend go after an aluminium type. A carbon type is just for the ultimate weight reduction purpose. So, the aluminium do best of both worlds. Go for it.

Differential
Depends on your purpose, but the top trims of Silvia/Gazelle (usually the "K" in Japan, from the card deck,  King) came with a limited-slip right from the factory. Same for the "A" (informally "Ace", a version tuned by Autech Nissan, exclusively in Japan). Crappy thing is that you really must not get anything with a HICAS on the rear, so I'd rather play safe with a stock rear suspension on a very basic trim. It works very well, but that's only if you're into shaving that 0.010 of a second at time attack. Just get a basic LSD. Whether you'll use urethane or rubber bushings, it depends on your feeling at the wheel.

Weight
The S13 is about 1100-1200 kg on average, depending on the trim. If you ever watched that video from ChrisFix and his weight reduction on a BMW sedan, and finally got your confirmation that you can shave some 250 kg from any car you see on your life, you know you can pretty much bring the Silvia/Gazelle to low 1000 kg sharp and just a bit less than that. But this part is completely optional on your part. I know its mostly a 2-seater sport compact just like Prelude, Eclipse, Miata, Impreza, Celica... but Silvia is just one among them and it doesn't make much difference. I mean... you'll probably never use the rear seat beyond storage, like an extended trunk so... feel free do to the weight reduction. Its a very optional choice.

Engine, Exhaust, EFI, ECU
The problem is that most export versions of the S13 often were sold in the american market with the crappy KA24E or KA24DE (2.4 litre) engine, whereas around the world they had CA18 (1.8 litre) or SR20 (2.0 litre) engines. Also, these engines came in other Nissan models from the time, so a swap is usually easy. But you really need to get rid of the 2.4 litre. I've seen countless chaps try to push the best of 350 hp on the KA24DE which is the 16 valve DOHC version, but since its a car that is so light, you probably will feel the need of a high revving engine. Anything with a square or oversquare bore/stroke proportion will be good. Also, this car is excellet at 200-250 hp at best, so there's no need for anything beyond that. Don't even mind about putting a large exhaust pipe. Its worthless and I really dislike the practice.

The final result?
It always depends on your personal taste. I can explain on a post why I actually enjoy the true sleeper car on a more detailed context. Nowadays its called OEM+, or "lightly tuned", or any sort of thing like that. That's because I understand how the market actually works, what are the real price cap on these modern cars and for how long most common people will keep them. Its not exactly because they get so much attention, rather its the contrary; the least attention you can get, the better you are enjoying the car by yourself.

If I can bring that change to the car culture, it will be a good for everyone around. I think its due to how my expectations do not fight the reality, even if the reality does not make up the mind of all people around me. Maybe in China, maybe in Korea, maybe in Japan. But I'm not residing there at the moment. I want but its expensive even to get away from Brasil hehehe. The RPS13 is not much different from Prelude, Celica, Eclipse, Impreza or Mystere, but I doubt if people in the occident will ever take my words seriously. Not that I'd want that to happen, unless I'm working actively with cars.