Fuel Stabilizer vs. Octane Booster?

OK, I have two older Hondas (86 Prelude Si/90 Civic Dx) that have full tanks of premium, but neither see a lot of driving action. Both are due for emissions testing in the next sixty days.

If added tomorrow, which is the better choice to ensure the fuel-quality won't be a factor in the testing?

Since I don't have a can of either around right now, does a booster compound have any of the same attributes of a stabilizer?

And, yes, I'm going to run SeaFoam through the throttle-bodies and manifolds, then take both for a nice warm-up drive before the tests.

Any ideas?

One of the most effective "tricks" is dumping a bunch of alcohol in the gas (fuel stabilizer is mostly likely alcohol),, this causes the car to run lean (not sure how much a computer controlled injection can compensate for this). Obviously this will make the car run pretty crappy, so some idle adjustments are likely. Apparently up to 25% alcohol is suggested. I tried around %25 in an 87 Mazda and it seemed to do wonders.

Clearly having full tanks is not ideal for this, having the cars as empty as possible is actually best (less alcohol and easier to thin it out afterwords).

Octane booster is a joke. When they talk about adding "points", they mean "point 1 octane", not "1 octane point".

I.e., if the booster says it adds 2 points, and you dump it in a tank of 89 octane, you get 89.2, not 91.

I would say Sta-bil.

Any reason for running premium in those two cars anyway?

Skip the Sea Foam until after they fail the test.

Drive them until they have less than an eighth of a tank of fuel left and then dump in a bunch of bottles of Dry-gas or any good quality gas line antifreeze. The better stuff is like 90% Isopropyl alcohol.

I did this with a very high mileage 89 Civic Si and my hydrocarbon emissions measured zero, because, well, I wasn't burning any.