No your wrong there they arent check them up. Near same pricing as gsd-3s. That doesnt make them a cheap tyre. its not all about what you think it cheap aswell as Neil said Alex's 600bhp car runs them no problem. I personally dont think they are that great but some people love them. Different people drive differently and need different tyres to suit their driving style or what they need from a tyre.
I have 'checked them up', and they're a cheap budget tyre. They have a poor compound that doesn't like heat so you'll never be able to work them enough to get them proper sticky without them melting, they have floppy sidewalls so you're always increasing the internal pressure to get any turn-in from them, and (whisper it) they're not actually that good in the wet either. Alex may run them on his car but I bet he doesn't get anywhere near adequate grip on them, with his monster you'd need R888s or full slicks to get that kind of power down. They're a cheap solution if you just want something to kill off on a trackday and don't really care about outright pace, which I suspect is how Alex uses them and I would too given how quickly his car must go through rubber, but don't mistake that for a quality tyre.
At least you're right about different tyres suiting different driving styles, but we're talking thousandths of a second at the top end of the market here (i.e. the difference between the 050As and the PS2s), not the basics between a budget tyre and a premium one. Have you ever driven in anger a 350Z on the VUS, PS2 or 050A back to back? I have, and the difference is night and day. The FK452/T1R are cheap budget tyres, simple as that. If they were that good do you not think that the big manufacturers would put them on their cars from the factory? They don't, because they're not. By all means put them on your car, but you're sacrificing grip, turn in, feel, and reduced stopping distances in both wet and dry conditions. Yes, they're legal, but that doesn't make them a good companion for the Zed.