If you have a stock KDX head [stock compression] and the throttle response is a bit too much for you --say in loose dirt --an octane booster will help soften the hit & give you less tire spin. High octane fuels burn slower & produce less power in most engines. See Eric Gorr's website & his treatise on Fuels & Fuel Myths.
if you want more power in a fuel, get one with more oxygen content.
Higher octane will not give you more power. On a stock motor, try a colder heat range plug to help you out. When you have increased the compression, you will then need the higher octane fuels to keep the ping out of the motor.
I have tried a variety of Octane boosters and found only one that works. I found my KDX more responsive when running the combination of 93 octane and Pennsoil Outlaw Octane booster. Iknow what other readers have stated but found a definite difference in performance with Outlaw.
Oxygenated fuels (as used in oregon in the winter months) are known to be crap. Vehicles run worse with oxygenated fuel. My (used to be) bracket car has fits with it. It's not a radical motor: is 10.25:1 static compression with about 190psi combustion pressure at cranking speeds...about 375HP out of its 340 inches (good enuf for 12.9s in the 1/4 with a 3400lb car).
This is due to........?? Alcohol being hygroscopic? The reduced BTUs available from alcohol?
I don't know that '6% oxygen' number in VP Ultimate is the same thing as an alcohol added and thus termed 'oxygenated' in the crap that comes out of the pumps hereabouts.
I used an octane booster on my old 78 175cc Suzuki to get the recommended octane requirements. I called several of the companys that sell the stuff and most said not to use them in my 2-stroke. One company said it was ok. I did use it at least until the piston seized. I think it was called 'the good stuff'.
One last thing for future reference. If you are going to steal someone else's words you might want to pick someone who actually knows something about the subject matter, because it's clear these guys DON'T. :confused: :)