5:1 pump swill to race fuel ratio seems almost worthless to me. That's like pouring a liter of Perrier into the tub of old bath water... Lots of folks mix half and half, or just run straight race fuel. Half and half is effective for helping eliminate pinging, but the resulting octane won't be a linear formula. ie, 1 gal of 90 + 1 gallon of 100 won't necessarily yield 2 gallons of 95.
If you do a search using "race gas" or "race fuel" as the keywords, you'll get enough hits to be reading for days. Also try clicking the "Eric Gorr's" link to the left and look under the tech articles link for Rich's race fuel pt. 1 paper. :cool: