last i read, the kazuma elimates the cat, so from who i read if from, they are either right or wrong.
why do you think it's illegal and for race? race cars have no cats.
otherwise, anyone could make a kazuma exhaust from a TRD
by takin the resonator off since the rest of the piping is the essentially the same.
kazuma does not gain 20hp at the wheels, all it does is free up more flow and gain a little more than an axle back.