Secondaries aren't a "stage" of VTEC. More VTEC motors come without a variable-length manifold than with it. Hell just the sheer multitude of B16's out there probably is more than all other VTEC motors combined. Add the B17, B16B, B18C5 and F20C and yeah, that's a lot. BTW the H22 and H23 both have a variable manifold and the H23 isn't even a VTEC motor.