i actually have a b20b in my car... not a d-series.....
and i got around 28mpg with the p28...... but average about 30 with the ls (pr4) ecu......
the p28 ecu ran with the engine check light on though. it was for the vtec stuff (obviously because the b20b is non-vtec)...
Anyway, just weird how I dropped 10mpg. I mean timing can affect gas mileage, but 10mpg? that is a lot....