rotaries run MUCH hotter than a piston engine.. running them rich cools the exhaust, which will make the cat last longer... the exhaust is still hot enough to cook off excess without damage to the cat. the only reason it runs rich is emissions.
by all means lean it out, you will get more power. you might light off the cat and cook it though, so keep it slightly rich if you actually care.
mazda is only running it this rich because of emissions.
Also make sure you have the latest PCM update. they fixed a lot of the problems and did lean it out better since M on.
Last edited by Aseras; 05-24-2006 at 01:56 PM.