Tuning without a wideband can be a bit tricky, and I probably wouldn't recommend it anyway. I suppose you could just lean it out a hair, but you could just as easily buy a wideband for like 40 bucks (one of the crappy VW ones that don't work well enough to actually be used in a honda) and hook it up to a DMM to get your info.
Generally I wouldn't call for adding a turbo unless you're downsizing the engine. While it can be more efficient in certain ways, the primary efficiency we're concerned with is fuel efficiency and not thermodynamic
. Most ECU tables I've programmed will really start to dump fuel on when you get anywhere near boostland, which isn't want you want. I haven't explored the possibilities exhaustively, but I suppose that's because I never say much possibility there.