Good job. Other tricks will come to you and you'll get better and better economy. I like the challenge of it all, just as I occasionally like the fun of banging gears. {OK, not so much banging gears as I used to do.
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The only mod I've done to my car has been to adjust the nut behind the wheel. I'm consistently 7+ mpg over EPA highway rating. I find that with a manual trans, beating EPA is not too tough. But then, most of my driving is rural roads, very little city driving.