on the contrary, narrowbands are pretty accurate, but you only get a lean/rich indicator, and mine gets lean while accelerating at full throttle.

how lean? I don't know.
I cured some of the problems by plugging the evap valve, it should be some leak thru there. I'll repair it later.
at least its driveable enough to do burnouts
I never saw a project with the laguna TB mod, I wonder if it really exists..