It's hard to get the cells equalized in a stick pack since you can't get to them individually. 'Zapping' them like the matchers do can only be done one cell at a time. Realize too that the stick packs are made from unmatched cells to begin with - the best cells (10-15%) after zapping and initial cycling are put together in matched race packs, the rest are more or less randomly assigned to stick packs. Some stick packs are just better than others because they happen to get better cells.
I've gotten better performance out of stick packs by slowly discharging, then wait overnight and discharge again. This allows the cells that still have life to sort of equalize. Or use one of those cycler/equalizers that are made specifically for stick packs - they do help, even if they take 5 hrs to discharge. I see MuchMore makes one that allows you access to individual cells by punching holes in the shrink wrap and grounding to the individual battery cell cases.
Then you can charge the pack at a lower rate, like 2 amps, to get a little more power into them. The slower rate allows all the cells to absorb as much as possible. I used to charge mine the night before then re-peak them at normal amps right before the race. I'd usually get them to take in another 500 mah or so doing it that way, and batts have noticably more punch when they're warm off the charger.
GV2 Pro, XXX4G+, Blitz SCT, CRC GenXL