Berk HFC/CBE...A/F?
 

As I understand it, exhaust-only mods will not affect A/F much. A tune would not be needed. Is this correct? If not, how will they affect it, and does anyone have a before/after of a dyno showing A/F with these components

I don't have any proof (aka dyno), but in theory, any additional airflow gained from reduced backpressure would still be metered by the stock MAF sensor, and fuel would be adjusted accordingly.

Intakes on the other hand, tend to alter the airflow at the MAF sensor itself, causing either a lean or rich condition unless it is carefully designed to replicate the flow of the stock intake system at this section. A custom tune should be able to make up for this if done well.

For the MAF sensor to change A/F it would need to actually have its intake flow change, and Im not sure just a CBE alone will do that as there is still probably a choking point after the MAF before it gets to the exhaust. It might change it a small amount but pprobably not enough to warrant a tune. Add a better flowing intake and or HFCs then yes. When my car was stock the inside tail pipes would get black but after the CBE and HFCs they didnt get black anymore so the car did lean out some. So for you with a CBE and HFCs it will be fine without a tune but with the tune you might add about 10 hp.