I Got a pretty good deal on a boroscope, and decided to take a look at the cylinders while I'm working on this Mazda. I saw that cylinder 1 was very clean, cylinder two and three were definitely carb'd up with three being the worst. 4 was not so bad, five and six were clean on the left hand side with slight carbon built up on the middle to right.
So I decided to do a piston soak using Berman B12 and marvel mystery oil; it was pretty cool seeing the particles moving around in the solution.
From what I can gather, using Bernie's cleaner has helped to dissolve some old carbon in the crank case, and helped the flow of the injectors.
Still on the quest to save this engine from Pre-Cat failure of bank 1; Envy has come along way.