300 is what I have also been told. Can't go bigger really. Just tried doing that as my opriginal lockersac busted a seam. (7yrs old) Tried everything. Most of the bigger sacs got nasty airpockets in them and forced my locker open very annoying. I like just flipping the switch and having it fill til it ejects out the overfill. Nice and simple. The factory one fills the space the best I think. Just costed me some $$ for a new one though. Gotta love MC. Fly high wouldn't sell me a custom sac with the MC dimensions even though they make em and are the supplier for the MC systems. Thought that was kind of bogus, but hey guess they want top $$ too.
Does anybody know what the stock hard tanks really weigh? I just pulled them out and replaced them with sac's and they dont look like they hold 250lbs. I may fill one up with water and put it on a scale.
Out of curiosity, I just measured my hard tanks that are out of the boat. I broke them down into two shapes (where it cuts up for the floor) One dimension was 17.5 tall x 26.75 length x 10 width1 and 5.5 width 2 (7.75 avg) = 2.1 cubic feet. The second part is 15.75 tall x 11.75 length x 10 width1 and 6 width 2 (8 avg) = 0.86 cubic feet. The combined cubic feet for one side is 2.96 or ~ 3 cubic feet. There are 7.5 gal per cubic feet and water weighs 8.3 lb/gal so each one comes in at 187 pounds.
I definitely think it is more on the 400 side as well.The bag goes all the way up to the bow cupholders and from how round it is,I would say 400 maybe even a little bit more. but who really cares,just make sure it's full.