i think if you really want better mpg you should do something worth while. like research what tuning software is out for the car you drive and then pick up a wide band o2 and learn to turn your car.... along the way your own driving habits will change too. you will be suprised how much the factory tune can be improved on once you get the cat off and tune for it.


the factory is so hog tied by the epa that even the old 90 gm ecm's had a highway mode coded in them to make the car run at mid 16:1 and full egr once it was safe to run there. but the epa made them disable it by setting the coolent enable temp to 255*C because they said it was bypassing the cat and thats not allowed.

just enabling that option along is netting most people over 4mpg in mixed driving. more to be had with a few mods.


plus your learning a useful skill along the way... which seems much better to me.