I'm currently running 2 sets of rims and tires.
Set 1: Ap1 rims w/ REO-1R's
205/55/16 front
225/50/16 rear

Set 2: Ap2 v1 rims w/ Falken 912's
225/45/17 Front
255/40/17 Rear


I didn't buy the 912's (set 2) for performance, but one thing I have noticed so far: these size 912's actually induce more understeer then the REO-1R's (set 1). Is this even possible, or am I just imagining it?

 

It's very possible. You have more grip in the rear compared to the front with a 30mm stagger on the AP2 wheels. The difference should be fairly minimal though.