Hey Yodta,

Yeah, I checked my odometer reading several times with my GPS. I think my calcs are probably within 1% accurate, average. Your mileage is very similar to what I was getting with my 22R, DT header and exhaust.

I also tested 87, 89, 91 octanes and can't say that I really could calculate better or worse gas mileage. In the summer months here I needed to run 89 to keep my 22R from pinging just a little. I had my ignition timing adjusted right at the top end of advance scale - about 28 degrees.
Gnarls.