If, on a Royal Guard Interceptor (with Title), I grabbed an Experimental Interface and an Engine Upgrade, would it let me boost at this point if I had not previously boosted during my turn?
Question of the Experimental Interface
No, engine upgrade itself is not the boost action, it is adding boost to your action bar. EI allows you to use upgrade cards like 'expose' that have the header "action:" in them.
...but interceptors already have the boost action, what's the point of the engine upgrade?
...but interceptors already have the boost action, what's the point of the engine upgrade?
He was asking if EI, which lets you use Action: abilities granted by cards after you've already taken an action, to trigger the Boost granted by Engine Upgrade. The goal, I imagine, being to take something like Predator/Outmaneuver, engine upgrade and EI(via royal interceptor title), and be able to say, barrel roll, then EI to boost.
tl;dr can you (non-boost action here)+boost via EI and EU, thus saving your EPT slot for something that isn't PTL.
The answer to which is no, because Engine Upgrade isn't an Action: prompt upgrade, it says right on the card it adds Boost to your action bar. That proposed Royal Guard Pilot configuration above has nothing, actually, that EI is able to activate.
^^ Otacon is absolutely correct. The Engine Upgrade is redundant and that configuration would be 7 points of GNDN.