Has anybody heard anything about these?

My car is barely three years old, I doubt the spark plugs and fuel system and that shit.

Fuel filter can still be full of shit if you have used low quality fuel OR you may have just picked up some shit from around the place, If the plugs haven't been seen to they might be due depending on what style they are.

What kind of car is it?

People who understand mechanics should stop thinking that knowledge translates over to electronics.
It has nothing to do with the way the current has to travel, or the loom etc.
The mod only modulates the signal sent to the ECU, tricking it into accelerating the car faster. Mk7 Golfs have a huge improvement, and are notorious for the otherwise shit throttle response.

'13 Sonic 1.8L manual

Pls leave, a fuel filter or plugs is not going to give poor throttle response, it will cause a misfire. If the fuel filter was blocked that badly that it affected engine power, the check engine light would be on as fuel trims would be so far out.

And people who understand neither should comment on neither. Naming a car model it 'works on' doesn't mean you're not full of shit. If you can explain what particular signal on what component is at fault, I'll eat my hat.

It works on every model. As I explained above, it simulates the throttle being pressed further. The ECU sees this as more torque requested than usual at this physical throttle position. It's quite straight forward.

The throttle position is read as a resistance determining position % though. You can't go higher than 100% because then the ECU will throw a 'signal unfeasible' code and it won't make a difference. So effectively you could just press the pedal harder.

It's not actually read as resistance. Correct, it can't go higher than 100%, and I said the exact same thing above, just press the pedal harder.

Listen here dickshit, I've got a masters in electrical engineering and I'll tell you exactly what these things do. You plug them into your tps, and out into the regular loom. The box then adds normally around 20% additional throttle to any input above a certain percent (usually around 20). So at 0% there's no change, but one you hit 25% real throttle, the ecu is getting a signal for 45% throttle. It feels faster just because it's accelerating more. go WOT in a car with it and a car without, It'll accelerate just as fast in both cases.