Is it possible to upgrade only NW stack without upgrading PI?

Dear all,

We are currently on SAP PI 7.1 EhP1 with Netweaver 7.11 SP10.

As a prerequisite fpr an ECC Uprgade to EhP7, SAP says " When using SAP Portal, SAP BW or PI in conjunction with ERP 6.0 EHP7, the underlying Netweaver version of these systems must be NW 7.30 or higher before upgrading to ERP 6.0 EHP7"

Is it possible to upgrade only the NW stack to NW 7.3 or 7.4 without upgrading SAP PI to 7.3 (or SAP portal or SAP BW to the next available version) ?

Thanks and Regards,

Reena