I'm starting to drive my car a bit now and the gas tank is headed towards fumes - it gets surprisingly good mileage - and it will need replenishment soon. The price difference of premium vs the 87 "regular" almost makes me sick -$.30 to $.60 a gallon more. What am I really giving up between the 87 and 91 octane? The engine is not particularly hipo with 9.0 compression ratio, a Ford 'E' camshaft with 1.7 rockers and an Edelbrock 1405 then fired off with a full MSD ignition system. My guess is - not much as long as I drop the initial timing a degree or two, 10 to 8.

Comments from the others here??

(and yes, I AM cheap {think broke}with a new $$$$$ roof being installed on my home as I type this)