Coupled inductors have been used with impedance-source networks, extended from the earlier Z-source network, to keep their shoot-through times short, while providing high-voltage gains. A commonly stated requirement for these networks is that their magnetic couplings must be strong or their leakage inductances must be small. This is often difficult to achieve in practice especially at high switching frequencies. It is therefore necessary to understand the effects that leakage inductances have on the performance of these converters. In this letter, we address these issues for the latest Y-source network, showing in particular that voltage spikes will appear across its switching devices in some, but not all, cases. Experimental results verifying the findings have been obtained and presented at the end of this letter.