The flowtechs are the old Hooker Headers. There should be more info searching Hooker Headers.
They have larger tubing and a longer path to the turbo creating more turbo lag and making your car slower.
They do flow more than stock headers which is not needed unless you’re running low 9’s or faster, but even at that level T/A race headers or custom headers are you the norm.
Keep your stockers unless they’re beyond repair.