well, to put it a little less bluntly and a bit of an explanation:
plugs and wires do not boost HP, a common misconception, they allow for a more efficient passage of the current from the coil pack (HEMIs) which will put less static strain on the coil, plug, and wire. It increases the life of plugs and the Iridiums, E3s, etc. simply have a hotter (more intense) spark than stock which in conjunction with low-resistance wires and higher efficiency coils means a hotter more efficient burn in the end of the plug (not the cylinder) = less carbon coating and replacement. your Q input wont affect the cylinder's efficiency as the ingnition temperature is based on the fuel/air ratio and as long as you have that then everything else is extra. if there is any boost in HP it's negligable but if you had dirty plugs and switched them out you'd notice a gain.
the synthetic lubes are a must as they don't break down as fast as naturally produced does and just outright work better at keeping everything coated and reduces heat generation. The only thing you have to look at is what weight and vis you need based on your environment (-40 deg is not happy for trucks i've found)
Other mods that are musts are the intake and exhaust. do the research on the exhausts first, as the flowmaster uses an internal baffle system which sounds great but really axes the flow. Also, if you have the MDS then you can start sounding like a honda civic when you switch to 4cyl if you don't have the right muffler.
the only one i would add to the list above is Borla: well tuned but expensive.