i think otherwise.
i went from a china core (600x300x76, bar and plate) and custom piping kit, to a trust v-spl kit (600x300x76, tube and fine), and i notice the difference; performance wise.
increases in responds, also the v-spl kit flows much better, as i had noticeable boost increase 1-2psi, in normal driving condition. i did not change anything but the cooler on my car, so personally i think if your doing it on the cheap go head buy the cheap china kit, but if you want to do it right, send the extra cash.
my 15cents