The 3600s will be able to hold about 4500mAh. Also, if you intend to race, you want your race packs to be the minimum to complete the race. This will give you lighter weight without giving up the punch. For a race, 3300s would probably work well. Maybe even lower mAh. You only have to go 4 laps, probably 1 or 2 prior to race, for about 6 laps.

3800s yield good competition results. One individual pulled the boat out of the box, stuffed the 3800s in her and came in 2nd. He eyeballed the trims.