it looks like it's ballast upgrade season, with so many posts.
I thought i'd share my experience, since I was a bit scared to do it, but everything well.

i picked up the kit from wakermakers.com (http://www.wakemakers.com/supra-moom...m-upgrade.html) and watched carefully the video on how to drill thru the hull:
http://www.youtube.com/watch?v=r8opr..._CEimQ&index=4

thru hull fittings location:


Pump location: the middle pump is higher than 2 others to allow for room for the hoses.


I installed a Y valve to control filling the center/front ballast and the 400 bag under the seat (on the left side, mostly regular surfers on my boat)


I didn't change the 3/4 hose going to the center/front bag that was too much work... but i did add a vent at the front of the bag, hooked to original drain.

I found it very useful to use a pvc pipe cutter like this http://www.homedepot.com/p/t/2023518...7#.UX9IhN7n_IU to cut the hoses.

the 750 bags now fill up in about 5-6 minutes, which is about 1/3 of the time than before.
that was a very fun project!
It's really worth it, i don't regret at all.

Full result in pictures on flickr: http://www.flickr.com/photos/jixim/s...7633369161373/