When commuting, it is all 25 to 40 mph city/suburban streets. But this mod was intended for longer contsant high speed (50-70 mph) drives. We drive every so often to Portland, which is a 200 miles round trip. Even though it is 70 mph for 75% of the way, I can get away with puttering at 55-60 most of the time. It would just be too much effort for the gain I imagine for commuting - especially since it would be my wife who'd have to do this. Riiiight.....
I believe that I have basically achieved 90% of what is possible from the car in its stock form. After it is paid off and the novelty has worn off, I may consider 'basjoos"ing it to move to past "impulse power" and into "warp 1.0". But that involves too much time and money (and intermarital strife) to be worth saving a few dollars at the gas pump. Maybe when gas reaches $10+ per gallon the relationship may be in favor of modding, but even then the KISS answer would be to drive less.
Then again - since when do men take the easy way to do things.