Hemigreg I find mostly the same. On my FI 89 Honda accord still getting 2 mpg more with acetone. On the 77 chrysler lebaron I'm getting almost 8 mpg more 5 mpg on average. TQ and lean burn intact. Also as noted I have gone down from running 93 to running 89 octane no ping audible. These are city driven calculations.
As far as how much I use I am using alot less then 20% but i have started to just measure by eye and go with that. I am very happy with the results.
I have been running 3 tanks with. 3 tanks with out and can see a notciable differance first fill up on the switch.
Only vehicle it hasn't worked on is the wife's 99 astro van awd. Ran 4 tanks with acetone on the way back from Miami Fl. and did not see any noticable differnace. Dunno why but I blame GM.
