 Other series configurations exist where no bypass system is employed and both compressors are in continuous duty.As a result, compounded boost is always produced as the pressure ratios of the two compressors are multiplied, not added.In other words, if a turbocharger which produced (pressure ratio = 1.7) alone blew into a supercharger which also produced 10 psi alone, the resultant manifold pressure would be (PR=2.8) rather than (PR=2.3).