I picked up one of those when I got the RX7 running last year. Definitely one of the better investments lately!
Do you see a noticeable improvement with the Water Wetter? Opinions are mixed in the rotary community. Many are of the opinion that at least some ethylene glycol is necessary to lubricate the water pump. Although I haven't seen the source there's a claim Mazda Motorsports recommends a 90/10 water/glycol ratio.
Water wetter, or something comparable, is a must for engine longevity. Nearly-pure water is superior to 50:50 for heat transfer capacity, but you need a little lubrication and corrosion inhibition to have it last! My FSAE team, and Lemons team, both transitioned from pure water to water + waterwetter after observing significant corrosion using pure water. My Lemons team also observed superior water pump life after the addition of waterwetter.
Interesting data:
https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html
I bought this one a while back but never had the opportunity to use it. MAN it makes life easier.
Right? On my MR2 it is the only thing that makes bleeding that insane cooling system tolerable.