I just picked up one of these as well and saw that in the instructions, but I don't recall seeing an arrow either. I'll likely install tomorrow morning.
That's the million dollar question. From what I've read on here the stock box outperforms aftermarket at the drag strip. The aftermarket guys all say though that they noticed better throttle response and a touch more low end torque with theirs on the street. The stock advocates say the idle IAT'S are much higher with a aftermarket when idling or in traffic. My IAT's are running over 20 degrees higher than ambient when cruising around though and I've seen some guys with the Steeda say they are only running about 4-7 degrees higher when cruising...
I have the Roush and I'm usually only 2-3 degrees above ambient when driving. Obviously it goes up while sitting and idling but goes down quickly. I didn't have a CAI on my 13 but I think this looks great under the hood so I did it. I'm happy with my purchase.
If I'm going above 40mph, my IAT are indeed just a few degrees above ambient. Of course, this is dependent on the accuracy of both the temp readout on my dash screen and my Sync screen.
