Go with the Yakima kit. CX7 bars do not work.
The Yakima kit (landing pad 11, control tower, ...) works great, which is what I'm using now.
The Genuine Mazda Accessories 0000-8L-M01B Roof Rack for CX7 does NOT work. See pics of my failed attempt below.
Here's what I did:
First pry the trim back and mark the mount spot to drill the holes. You don't have to remove the whole thing just look for the black mount points and pry it back.
The trim is black plastic backed by aluminum so I got a new Milwaukee Thunderbolt Black Oxide Drill Bit - a bit oversized (7/16) - to drill through the plastic/aluminum trim and give me some room for measuring error.
A thin strip of plastic plexiglass (from Home Depot) was used as backing behind the trim so the drill didn't punch through and mess up the mount points.
First I tried the CX7 bars "Genuine Mazda Accessories 0000-8L-M01B Roof Rack", which did NOT work out:
As you can see the 0000-8L-M01B Roof Rack rear bar is way too wide:
After I gave up on the CX7 bars, I used the RackAttack Yakima kit with landing pad 11, control tower, fairing, and powder hound ski mounts, etc.
Here's 2 of the landing pad 11 mounts installed:
And the full Yakima setup:
What really nice about the Yakima landing pads is you can remove your rack in 60 seconds and store it away in the off season or between trips:
Definitely recommend the Yakima rack system from RackAttack for Mazda 3 2014.