Started mixing Toluene with 93 octane, aiming to create 95 octane or higher. I can notice a difference in performance, especially on cold mornings. Exhaust sounds louder too, I should've started doing this a long time ago! Also added some Lucas stop leak periodically in with the oil, and the occaisional knocking at startup seems to have gone away. Pretty impressed by this product, I was skeptical at first, but it has calmed the engine down a bit. Spring time will see this car more or less being retired, in favor of building my RS into a tarmac crusher.