Hey look, your car needs vitamins.
I hate to hijack this thread, but since it was brought up already.
This is the biggest load of malarkey I've heard to date:
What this catalyst does, for our purposes, is to cause a change in what is called the "in-cylinder rate shaping" of the combustion. This, in turn, provides for a 30% increase in pressure on the down stroke of the piston, in a time frame slightly altered from a non-catalyzed state. This results in the improved performance.
In order to change the cylinder's combustion chamber, and increase pressure by 30%, you would need to decrease the combustion chamber size from the typical 64cc to 46cc, that's an 18cc difference. (for a small block) from 118cc to 76.7cc, a 41cc difference (big block)
That's something that they're "catalyst" cannot do. You'd had better luck taking your heads off, and welding a blob of steel into the center of the chamber. If I'm wrong, and they're describing a 30% increase in compression ratio, then you're talking a very high ratio, in the order of 10.4:1 from 8.0:1, which would be tough to pull off chemically. Even if it were possible, it would cause your engine to ping, which would force the person who's convinced that the tablets work to buy a higher octane gas to stop the pinging. Forget you guys who already have a high ratio in the order of 9.5:1, you'd be looking at a new ratio of 12.4:1, which would have you running racing fuel. Tell me where the savings would be.
You'd actually get better results from the natural formation of carbon build up in your head.
I don't see how they figure this can work. Another snake oil remedy if you ask me.