If you don't want to break the bank I would say any of the mid range all carbon ICS style arrows would work just fine...........something like a Carbon Express CX, or a Gold tip XT will shed the weight considerably while still retaining plenty of KE for whitetail sized game.
A 27" 2315 with a 100gr head and 4" vanes will weigh in at about 500 grs, so you will probably drop around 130-140grs or so going to say a CX300 or a Gold Tip 5575 that would weigh in around 360grs.(if all else is equal point weight, fletch style etc) which will flatten that trajectory out considerably.[:-]

However with such a move you will pick up increased vibration and noise so you may want to keep that in mind (although the Q2 is a pretty mild shooting bow to begin with)

Maybe a better alternative might be a heavier weight all carbon shaft like a CE Terminator Hunter that will give you a more mid range finished arrow weight in the mid 400gr range........enough of a weight reduction that you will see a difference in trajectory, but not sacrifice the quiet and smooth shot you will get from your heavy arrows.