"Spec upgrades" refers to making improvements or enhancements to the specifications or features of a product, typically to make it better or more advanced. Full definition
Below is pretty much all you need to know about the major spec upgrades you can expect. (playstationing.com)
As expected, the new devices also come with the usual spec upgrades. (sammobile.com)
New flagship builds on the well - received Honor 8 with a refined design and spec upgrades across the board — while keeping the affordable price tag. (androidcentral.com)