i have a 3:73 also--i still get good gas mielage--actually alot of people go with a 4:10 on the modulars but id get a 3:73 over a 3:55 if your super worried about highway travel then just go with a 3:27 but it probably not worth the money to geat a 3:27....at 90mph i rev at 3000rpm and still get good mielage....the mod motors dont seem to mind high revving...