Ok Ok... go get your $100 fajita's and prop's...

I did find a couple of threads you will find interesting... (The first one is directed at your Yak)
http://www.rcgroups.com/forums/showthread.php?t=579706 (maybe you found this already?)

The second talks alot about your motor, packs and prop selection.. read up... maybe a 14x7 is really the way to go with your 3 cell packs?
Anyway... here is some good info...
http://www.rcgroups.com/forums/showthread.php?t=835764

Take note of the 4 cell info in that thread too... especially if your power-hungry.
They talk a lot about running 4cell packs with your motor... well, a bit of quick reading at CastleCreations.com leads me to think you have the 45amp "Pheonix" esc, which will also run 4cell packs. (There is no 45amp "Thunderbird" 3cell version listed)
Hell, even your Equinox balancer will take care of up to 5 cell packs.
Your motor, with a 12x8 apc prop, on a 4cell 2170 pack will put out a whopping 500 watts at 40amps - huge power for your plane.
In the end your pretty much all set for 4 cell - just make sure your field charger will handle 4 cells.
(If it doesnt, goto Fmcdirect and get a Cellpro 4s - excellent balance charger - I even bought 2 of them)
All you need is the packs, the bec and maybe a charger.
Keep in mind, the electric motor and esc, just like glow power... will outlive almost any plane you put it on.
So upgrading for more power is easy, now or during your next build.
As for getting 4 cell packs, go to hobby city.com and check out their Zippy 2000mha 4s1p packs... I have a bunch of their packs and like them alot - great power, half the cost, just buy enough to make shipping worthwhile.
(The hobby and city are together... I get **** anytime those two words are mated in this forum... go figure)