what do u mean by tuning sheiro? ecu re-chip? or hondata?
either one, I first tried vafc, then I tried chipped ECU, buth both not to my liking, so I spent on hondata. They all can do light tune, but I just wanted more features, that's all. I wouldn't really recommend hondata to anyone unless they like to tinker around with fuel maps, or is always using the unit to do a base tune for modified cars to see what to expect in terms of performance gain. some parts do work well, but it seems like there's a bit of work in terms of tuning to get it right, esp with intake and exhaust mods.
if tuning theory, it's something like this, get peak pressure in cyclinder to get maximum torque out. if you can play with fuel only, then use AFR to generate peak pressure. If you can play with ignition, then you can play with both. In the end, both systems work, it's just that one has more flexibility over another in terms of tuning for a more extreme system with cams and etc.