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 ( and watched carefully the video on how to drill thru the hull:

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 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: