Just get another stick of RAM and you should see a good performance uplift. In fact, you don't have to get DDR4 3200 stick because the 3450U only officially supports up to 2666 Mhz. So that will save you some money. Also, it looks like they are cutting cost because the unit I got came with Crucial DDR4 3200 8GB ram, not Goldkey.
In addition, if you need more storage, I recommend that you sell the SSD off and get a higher capacity one. I don't recommend installing the SATA drive because installing a 2.5 inch drive there means a significant amount of ventilation will be blocked. The design of the chassis isn't good because the fan is installed on the other side of the board where there is no ventilation other than the gaps between the edges of the motherboard and the casing. Under load, the fan works very hard to cool the CPU. For my case, fortunately it never throttles though the temp did hit 90 degs before.