So you didn’t figure out the trick
If you take a look at where the rear LCA mounts to the rear cross member, you’ll notice there’s a slit opening. This slit is a “just” big enough opening to allow you to insert an open ended wrench inside of the hollow LCA, which then catches the head of the end link and voila! I used a standard (14 or 15mm, I think?) Craftsman wrench so nothing special from an everyday wrench. You have to pay attention to orientation of the wrench as the open end side has a slight angle. A locking vice or helping hand is needed to hold it in place. Oh, careful not to over tighten or the wrench will get stuck -don’t ask how I know

. Once there’s enough friction to hold the end link without the wrench, remove wrench and tighten the rest to sepc. It was as though Mazda made that slit there for aftermarket end links (OE links use allen wrench to hold it down).
Review Update: I definitely enjoy this mod. There’s a noticeable improvement in the rear rotating more on turns. This car is already pretty good on tight turns and U turns (folks like 0-60, I like small turn radius -go figure), this makes it even better

. However, I feel the car is not as stable as before. I’d summarize it as feeling a tad dart-y. This could be a mix of things, which I won’t get into. I’m sure some (most) of you are probably opposed to a beefier FSB on a FWD car but I think it will help to better balance the car if you upgrade the RSB. I can’t image what it is like on the stiffest setting of an aftermarket bar + OE FSB. Problem is you need to drop the front sub-frame to get the FSB out. Wouldn’t be as much of a concern if the car was new but can be an unnecessary challenge on a 5+ year NE car.