With modern ecus in the aftermarket you have adaptations. Set your target AFR and drive. It really is that easy.
My car has a 10 year old ecu with adaptive VE and is nothing near as nice as the stuff on the market now and really just driving it and letting the VE tables fill in takes a few days of daily commuiting to get 99% of it dialed in.
So a pretty basic map with a proper timing table and a few pulls on the dyno gets you right where you want to be. And with a W/B O2 sensor you can pretty much hit any AFR you want in no time.