I had Swamps build me some slightly fun singles when I ruined my splits running Easy Off or something through them. I also had them burn a chip at the same time, so I don't know where it came from, but I'm averaging a 1.5MPG increase. I hand calculate every tank, and I had the splits for 50k miles and the singles for about the same, so it's not a temporary thing, or a single tank miscalculation. The singles are slightly louder. If you want to know how loud, stand next to an OBS.
Don.
Don.
